I use a razer lachesis:
I set DPI on the fly with 2 of the 9 buttons -
I set up a profile to customize the DPI switches to -- 800, 1000, 1200, 1400, 1500
It will go between 200 and 4000.
I also have a custom polling rate set at 750Khz.
My in-game sens is set to 1.4 i think. I haven't checked.
I have been messing around with it lately, and I almost have it where I want it. The acceleration is a little bit too slow, but I am trying to find the balance between shooting accuracy, and being able to snap quickly for jumps. Overall in the last week, I have substantially improved my shooting stability.