Re: Is it fair to play live with a metronome?
The OP sort of implies that it's cheating to use a click, but I would argue that for someone who isn't accustomed to it, it's harder. So I'm not sure if cheating is the right word, because cheating usually implies making something easier.
Regardless, working with a click all the time is going to improve your time when you aren't playing with one. I would bet that the drummer who can play along with a click in all situations - live or studio - will play better time without the click than the drummer who says he doesn't need it and never uses it.