Like you mentioned a while back, One Piece fillers are pretty good. With the exception of episodes featuring the Foxy pirates, which I skip without any reservation, anyone not familiar with the manga might have a hard time identifying every filler episode, even the most obvious ones fit so well with the overall flow of the story.
There's definitely some compromise, you can tell the slight difference in quality when you compare my screenshot with yours.
*EDIT*
But it's still quite remarkable seeing such a large drop in file size resulting in such a tiny drop in quality. For me it's an acceptable compromise.