The beyer pads are definitely much more comfortable, but for the 680's, they totally killed the sound in my setup. The treble is way too sharp and forward sounding, and the bass is all but gone. It sounds fatiguing and I miss the tight solid bass, its just punchy but lost all body with the beyer pads. I went back to the crappy 680 pads since I'd rather have the sound signature I like with a bit of pain

But I have found another way to make the ear pads a bit more tolerable. Roll up cotton and stuff it behind the pads (kinda like a step in the Markl mod for D5000). This puts the drivers a bit further away, and doesnt press on the ears now and I can tolerate it for much longer now without any pain. I've also used the thin foam that came with the Beyer pads on the inside to tame the treble just a small bit. I like the way these sound now.
The headpad is still a big pain though, Gotta try the memory foam mod, I have some lying around somewhere from an old pillow. Might look stupid though in yellow.