I have the most basic mouse, and to be honest I can't see what a super gaming mouse could offer as advantage.
Though I am considering to by an $6 Aliexpress gaming mouse for the fun of it.
For me, the primary advantage is in the side buttons - in BF3, BF4 and BF1, I use the side buttons to switch between primary weapon, secondary weapon, my gadgets, the map, and map zoom. It means I don't have to stop moving to do those things. Being able to switch sensitivity on the fly also allows a player to switch between standard hipfire/pistol sensitivity and ADS sensitivity, which can really help accuracy. I hate snipers and sniping though, so I don't really use that function.
In browsers and the like, I can go forwards, back, switch tabs, reopen closed tabs, close tabs, close the window, go to my homepage, open the bookmarks folder, scroll to top/bottom of the page easily and so on.
That's the advantage - flexibility. A decent gaming mouse with sufficient buttons lets you do all those things. I generally find that the difference between LED and laser mice is, for all intents and purposes, unnoticeable. I never use the really high DPI settings.
The disadvantage is that most gaming mice seem to have been designed by Homer Simpson.