1. tookenza, wireless mice have never had any of the mystical issues that people have thought they do; the following is true that probably caused such 'issues' to exist in the first place
a) poor receiver placement
Wireless receivers don't like behind behind a big metal casing resonating with the hum of hard-drives and fans, with what amounts to a massive magnetic well, between them and the mouse. This is, in almost all cases, what causes reception issues for those trying to use wireless mice/keyboards. A USB extender cable works just fine if your receiver(s) didn't come on cables anyway.
b) 'lag'
Think about it, I mean, really think about it. If your receiver is right next to your mousepad and/or keyboard, the signals from your mouse/keyboard have less than 30cm to travel before they get picked up by the receiver and are sent along to the computer via (the same kind of) USB cable you'd be using for any wired mouse/keyboard anyway. The most lag that could be introduced here would come from crappy controllers converting the mouse or keyboard's signal into a wireless frequency and then back again on the receiver, and unless you're using the most crap of crap wireless devices, this is done at such a rate as to be unnoticable.
c) mental stigmata
If you're the kind of l33t k1dd13 that can't get over how perfect absolutely every aspect of your gaming experience must be, right down to the .xxxxxxx settings you put into the console for most games you play, then the chances are good that any time you fail it will be blamed on anything you can blame it on. It won't be because you quite simply messed up. It won't be because the other guy is genuinely just a better player than you. It won't be because something like server lag occurred (and let me tell you, 9/10 online gamers that reckon themselves to be the business, that I've seen, can't figure out when it is that they are lagging vs 'everyone else' or 'the server' are lagging, which indicates their technical knowledge is on par with that of a slug), it'll be because of this 'shitty wireless mouse' or 'this shitty wireless keyboard'. Yes, there are cases where something is wrong with how the devices are performing, but first refer to A and B
d) 'having to buy batteries all the time'
You're doing it seriously wrong if you keep buying expendable batteries for a wireless mouse. With exception to the most modern wireless gaming mice, the battery life on most wireless mice worth considering these days easily goes beyond 2 weeks. On my old A4Tech RF-SOP35, which had its own, special batteries, to satisfy its need for a full 3v of power, the thing easily managed to get 3 weeks on a single charge. I got that mouse in 2001 or so. On the MX610 (left-handed), a single charge could easily last me up to 2 months. On my G700? If I use it at its maximum settings for a nonstop gaming session, one day. The joke is that that first mouse I mentioned that I got in 2001 came with an aux cable allowing you to charge it from USB while it was in use. The MX610 didn't have this feature, but considering its 'shotgun' battery placement method this was a non-issue if you got 4 batteries in one rechargeable pack anyway. Most importantly, all three mice had battery level indicators - the one for the A4tech mouse wasn't so reliable, but you got used to how long you could use it, its cable was thinner and lighter/softer than an MX518's and it only took half a day to fully charge it, so it's not like it got to be a hassle. 'batteries dying in the middle of a gaming session' thus becomes a moot point; you have to be doing it wrong on a consistent basis, in which case you'd probably be the same kind of person that places the receiver at the back of their case, then wonders wtf things aren't working nicely.
Anyway, specifically regarding the article;
A polling rate of 500mhz to 1000mhz difference is neglible, yes. Going from the 125mhz that non-gaming mice use (MX-610/620, Performance MX I think, a variety of other expensive mice) does make a few differences, though.
1. The polling rate is essentially how frequently information is being sent by a device or received by the controller for it. The lower the polling rate, the fewer updates per second you have, the more interpolated (smoothed) output from a device needs to be. Yes, gaming mice have excellent processors in them these days to interpret the surface they're being used on and to send it as linear data to a computer, but if the polling rate is lower, that means they have to smooth the data more, which means you're ultimately getting less accurate information out of a mouse. To a degree, it also affects button presses, though you'll only truly notice the difference if you suffer from chronic "but I shot first!" scenarios where you can 'hear' your gun firing, yet nothing happens in game, and then change from 125mhz to 500mhz (or 1000mhz). For wireless mice, a doubling in polling is a doubling in the frequency of transmissions, so a halving of the expected battery life (iow: 1000mhz will sap a battery 8x as quickly as 125mhz).
2. DPI
Your article is wrong to say that nobody but the elite can play at a 5,700 (or even higher) DPI setting; yes, using such a DPI setting for desktop purposes is going to be a matter of micro-twitching to try and get your cursor exactly where you want it to be, but in most first person shooters you can at least set a separate multiplier for the resultant sensitivity to balance things out again.
On some mice, an increase in DPI does not translate to an increase in actual sensor updates per second (DPI is 'dots per inch', which in software-terms for mouse movement means 'how many dots/pixels the cursor will move relative to inches of mouse movement), while for sensor figures themselves it translates into how many updates per second of linear movement across an inch are performed; in other words, if you move the mouse 1 inch in 1 second of linear movement (no accel/decel), a setting of 2,850 would result in half as many updates from the sensor for the surface in comparison to 5,700dpi. This does have the side effects of, again, doubling your effective battery usage, potentially (though not necessarily) degrading the sensor quicker, heating up the sensor causing noise (go read about the ISO settings on DSLR Cameras and compare ISO 100/200/400/800/1600/3200 shots to get an idea) and getting skipping or a hyperactive cursor if your gaming surface isn't perfect, though. As a result, yes, most gamers will still use a lower setting, but when you have true influence over the DPI setting of the sensor, you will quickly notice that a DPI of 1,200 for rapid mouse movement is insufficient and causes skipping.
In other words, a higher DPI, for FPS purposes, is actually a very desirable aspect of a mouse if you intend on being able to rip your mouse around at far higher speeds than you would if you simply used a higher in-game sensitivity and 'twitched' to spin 360 degrees to walk away.
3. Side Buttons
If you've never used them you may not be able to understand. I'm not sure of how other manufacturer's software works, but when it comes to Logitech's Setpoint, it's been possible for years now to set up 'application profiles' for the buttons and to assign combination (keyboard) keystrokes to the buttons, where you weren't simply assigning them to 'generic button' or a numpad button, then changing hotkeys in your application(s). In the case of the G700, as an example, you can go so far as to set up macros and entire scripts, and using a profile switching button you can change the functions of all the buttons manually to suit what it is you need to do, without having to first fish for your shortcuts on your keyboard, allowing you to dedicate your other hand to a narrower set of commands. Example; on my mouse now, I have the four side buttons asigned to forward/back and tab forward/back for Firefox. Two of the other buttons are used to zoom in/out, which is relevant to me for when I'm in bed browsing, as I don't always have my keyboard at hand, and am instead browsing one-handed (yeah yeah, make your jokes). Seeing as the monitor is further from me than usual, zooming becomes a necessity. I also have, as a universal binding when not on a gaming profile, a 'document flip' button along the top. This opens a toggled version of the Windows Aero Flip interface, which I've gotten so used to using now that I simply press the button, choose at a glance which window I wanted then click on it in the stack.
Left and right tilt, which many Logitech mice these days have, is comparatively more useless. Fortunately, both buttons can be assigned to whatever else you want in the Setpoint software, so that's a non-issue, and just means you have two more conveniently placed buttons.
4. General wireless peripherals
I got the Logitech EX100 wireless keyboard/mouse combo last year September almost exclusively for the wireless keyboard. I ended up using the mouse as well in lieu of my MX610 for three reasons
a) The MX610 was beaten up. It didn't have 'skates' for a long time already
b) The MX610's tracking began degrading after almost 4 years of use on many surfaces, due to the mouse being 'too low'. The laser sensor it uses was optimized to be within a nth of a millimeter from the surface being tracked, and without skates and the plastic 'cradles' the skates were in working down, overall performance became unacceptable, and I lost the only (polished) surface it was able to track well on
C. Left handed mouse. I'm left handed. I got it thinking I'd be able to get used to using a mouse left-handed again, until I realised all the programs I intended on using it with were designed for keyboard-left, mouse-right layouts shortcuts-wise, and many shortcuts couldn't be changed... Gaming non-issue, but I'm not a hardcore gamer...