Well, for the sensitivity part, like what you mentioned, 2k-3.5k would be suffice for average people, im finding myself most comfortable around 2.5k dpi...
And for others, it depends on what you're looking for, lightings? shape? number of keys? texture? (rubberized or non-rubberized), customization? (ease of use profiling, switching of profiles, built-in memory or otherwise), sensor type? (laser or optical) and etc....
it all depends on you.... you can first find out what you want in your new mouse, then state the budget, then i think sifus here will give you recommendation....
Microsoft Intellimouse Explorer 3.0   
Haha... yea, at first when i saw mamba i was like "Da fuq? wireless death adder???"  

Microsoft 3.0 intellimouse, one of the best mouse out there. 
This is a question I want to ask too. 

After a year since I bought the DA, dust or some fluffy stuff starts to stick on the rubber mouse surface, I tried to clean it with some wet clothes but only made it worst, the rubber surface started to get sticky. I waited for couple of hours, still sticky, guess I'll start using a sticky mouse from now on.

Well perhaps I'll get a new DA-BE with Destructor. 

exactly what happened to my mamba. there's some suggestion online to clean with alchohol, which actually took off a layer of the surface instead. Do not use alchohol!

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Added on February 27, 2012, 1:07 pm

Thanks. dcided on M60 anyway. Price wise, 30 bucks higher than G700 which is not too bad. build quality for the corsair looks much better than G700.

My Razer DeathAdder no sign of peeling after 1.5years of usage
Its good...shape and sensor is good
Only bad part for me is the lift off distance
Try SteelSeries Sensei(RM399) or Xai (RM249)
Both have realy good sensor quality
But the bad part is the outlook can be easily corrupted if not taken care properly

Personally its too high for me
Imperator and mamba's lift distance enough for me
which is 1mm 
but i dont like mamba's weight

Nope you cant
Only sensei allows you to do that 

not sure why most people like Razer, why so nice about them? I own Roccat Kone and Kinzu, both of them are fantastic when compared to Razer mouse like deathadder, or any other mouse except mamba, coz i never tested mamba

i just got myself yesterday a Battlefield 3™ Razer Imperator & Battlefield 3™ Razer BlackWidow Ultimate...feels good so far:)

still likes 3.0 the best.

rofl :'x is facepalm.

Razer Naga Hex, Corsair M90 and Cyborg Rat M.M.O. 7, which one is better? I order Naga Hex already , hope my decision is correct.