I have some wrist pain from time to time. Raiding a few days a week is ok, but more than that usually wears me out. With my 360 controller I use this:
Add gamepad / joystick support to any game - Pinnacle Game Profiler
With ctrl and shift bound to the two paddle buttons, I get a total of about 24 keybinds for spells. I just use it for 5-mans, or grinding, but I wouldn't raid with it.