If I say I am a 5.10 climber I will climb any 5.10 with you in the alpine and I will not fail you, leading or following. The odds of me falling are extremely unlikely. That would be a 5.10 climber, in my opinion. I have onsigted 5.10's at smith but I do not consider myself a 5.10 climber, for instance, as 5.10 can kick my ass at times following at beacon rock, or at tieton, or at smith for that matter. Edit: in fact, it doesn't seem to matter what you call yourself. seems better just to consider the climb ahead and judge your abilities climb-by-climb, especially when you are teaming up with someone new for an alpine climb.