Hello,
Most ergonomics mouse (such as the evoluent) don't allow wrist movement, so you have to move it by rotating your elbow and shoulder. This is fine for most people but i never liked it.
What i use is de DXT (wireless), wich is really sensitive so you just move it with your fingers (no wrist, no elbow and no shoulder). One warning, i have small hands, so that may be a factor on why i like it so much.
Regards!