This. Got one myself and it has 2 buttons just below left click for DPI setting (raise and lower it to pre-determined min/max values in the mouse software).
Example:
My G9X is set to have 5 increments of DPI ranging from 400, 800, 1200, 2000, 3200 and 5700. You can change any of these values at will, plus lower the number of increments also if you want. I use 400 for sniping, 800 for running around, 1200 in ground vehicles, 2000 in aircraft and the highest settings for amazingly hard oh **** turns, all in BF3.
Due to the button placement and the software being really good, this is the first mouse I've owned where I can truly change the dpi on the fly to my presets, which are all set by me. You can also program the mouse to change the presets you want based on the application you load, which is an insanely powerful tool in my opinion.