[cutthegrass2]

That's interesting, i've just switched to using one and haven't noticed any discomfort, yet.

Are you laying your wrist flat when using it? I could see maintaining a fully pronated posture leading to wrist aches over time. I try and keep my hand as neutral as possible when using it, in realist i'd estimate my wrist angle off the desk to be ~45deg, then I use my middle and ring fingers on the pad.