Reading the "Superboy" reviews at the Superman homepage (I'm bored) about Smallville that I suddenly came across something. The reviewer mentioned that one particulaur storyline made Super"boy" became Super"man" in other words Clark Kent "grew up".
So, I'm going to ask the serious question;
When did everyone feel Luffy offically "grew up"?
Or is he still "a boy" and growing up?
We often see character call him a "man" but a lot called him "kid" or "boy" first and only changed their position after he trashed them around a lot.
For me, Luffy offically "grew up" in Water 7 when faced with the serious problem of defending a crew member from death. One could say before that there were many battles, both those could be read as being the equallent (excuse spelling). Though the previous battles were bigger, none were bigger then Luffy and co was and none were so much a wake up call for Luffy then Water 7. At Alabasta we had a city turning tits-up yet despite all that Luffy grew only in strength and not anywhere else. At Water 7, Luffy grew in strength, ideals and will power.
One could also argue he grew up the moment he left home, true, true he was taking a big step, but for the whole of the EB saga he was like a kid in a boat looking for some friends. But he was still learning about the wider world. The difference between then and Water 7 was that he didn't face the "big" people in the world who control everyone else.