I used to play inverted. Then I got into socom which defaulted to non-inverted and I never bothered to change it. Now I'm incapable of playing a console shooter with inverted controls. That doesn't bother me though since the question of which controls are best for shooters is only correctly answered when one says mouse and keyboard.

Strangely though, inverted isn't a problem for me when playing flight games. Mind you, if you use anything else for controlling a plane or space ship you should be ridiculed and shamed into correcting your error.