I have a R.A.T.7 (5600 DPI version)
I have Windows set at 8/12.. So relatively high up..
I use my mouse at 5600 DPI...
Other people grab my mice and can't use it... I turn my music up too loud and the mouse pointer starts to move due to vibrations in the desk.
It's very sensitive, but I love it, I rarely ever have to move it any distance, and probably use less than a 1/4 of my mouse pad (steelseries 4HD - standard size pad)
I just prefer it, it requires very little effort to move around the screen, and once you get the hang of it it's fine.
I tend to slow it down for FPS games, to maybe 4000, but don't actually play them that much. I just like to use my mouse at maximum because it works well for me
It took a while to get used to, but once you do you can't beat it
kd