I bought the G400v2 recently (v2 = the one without angle snapping/prediction) and I really like it.
It's shaped like the mx518 which had many fans as far as I know. I haven't experienced difficulties like with my old Razer Deathadder (couldn't do small movements somehow - I was used to laser sensors). Small movements and reaction shots are possible.
For those who prefer laser mice I can recommend the TTesports Black Element - that's the mouse I was using before. No flaws like (negative) acceleration and stuff. Sensor in the middle of the mouse and so on. The shape is a bit uncommon but I liked it. It's quite light though (I heard there are ppl who like their mouse as heavy as possible
).
I heard the Steelseries Sensei was quite nice too even though I personally didn't like it. I'd recommend buying the new version though with grip cover - the Steelseries Sensei [RAW].
Another really good mouse with some heavy flaws is the Roccat Kone+ (I think there's even a newer version out already). Great shape, size, and sensor.
BUT HERE COMES THE PROBLEM: I had to clean the sensor after every map of UT causing me to become paranoid and suck because I thought the sensor was dirty again.
I know several ppl with the same problem with the Kone.
In addition it seems to be poorly manufactured. It breaks quite often and fast
.
The new version's name is Roccat Kone XTD btw.
I stumbled upon an interesting new mouse today - it has the newest Avago laser sensor: the QPAD 5K LE. It has the same sensor as the Roccat Kone XTD but maybe it's better in terms of quality. Haven't tested so dunno... The shape seems a bit weird though
The problem with the G500 is the position of the sensor imo. It's positioned too far in the front of the mouse. And since you probably move your mouse with your wrist that means more movement of the sensor --> difficult for me to set my sens in UT and hard to do small movements. That's just me of course.
I once had a spreadsheet with the flaws and advantages of some sensors/mice but I can't find it right now. I'll try to find it and post it here.