Bullshit, bullshit and bullshit.
Whatever you're buying a mouse for, the first thing you need to consider is how it fits your hand (shape, size, weight). You might consider available sensitivities if you really know what you're gonna use that feature for.
Most of people advising you to buy some precise model just don't have much expirience with others.
And last, but most important, a gaming mouse won't make you aim better. The only way to improve your aiming, is improving your perception itself. Mouse movement will improve along.