Presently, I use a Razer Lachesis for gaming. This mouse completely perplexes me... well I suppose it reminds me of a race car for the reason I'll soon explain. Basically, the mouse is absolutely perfect for when I'm gaming, especially shooters. The feel, the shape, the movement (the feet are perfect), etc etc. However, as soon as a cursor gets involved (wow, the desktop, etc) the sensation is similar, although not as bad, as typing on a qwerty phone keyboard. Yeah, it helps some but it's not as good as others.
I've never used a mouse with this type of all or nothing behavior.
My favourite, a close second in gaming, is the Logitech G5. It was perfect. It did everything the razer did to maybe 95%, but it also was super awesome on the desktop too.