Perhaps make a small selection of armor and let the player choose his armor from the barber shop, rather than a direct conversion from the armor the player is wearing.
To diverge a bit, what class/spec is the most fun to level, in your own opinion?
For me, a feral druid is the best. You have almost everything you need. Cat form for killing mobs, with prowling if you don't want to engage mobs. If you get in trouble, switch to bear. The only weakness is that you have to shift out to heal, making it difficult to heal while fighting.
Enhancement shaman is ok. You lack the armor from the plate classes, but with water shield and the ability to heal while fighting, you can basically keep on fighting for a while. Totems are useful, but a pain to move around, so I don't use them a lot.
Atm, I'm leveling a frost mage. Not bad overall, but there is a gap between l14 and 20 for frost spells, so I'm starting to have some trouble. Hopefully it gets better after 20. Regularly eating and drinking is a pain though. I prefer classes with little or no downtime, which is druids and shamans for me.
I tried leveling a priest, but it's just not me. Got up to l6 before I quit. Non-existant physical damage combined with low mana efficiency makes it a chore for me to level. I do respect players that have leveled priests though.
As for DK's, rogues and hunters, I find the lack of a healing ability difficult to play. The classes are overall good, but to sit down to eat in the middle of patrolling mobs is just asking for trouble. I've ha denough trouble with mobs spawning behind me. As for the non-healing classes, hunter was the best for me, since it was rare for me to engage the mob itself in melee. I rely a lot on my pet.