man,
as little time as i get to do anything, i really dig the gym...its efficient, fast and a good way to hang with some buddies (pun intended) and get an "ok" workout...
I have to admit that when i'm climbing well on rock, i don't neccessarily climb well on plastic, but if i'm climbing decent on plastic i always climb well outside...
that said, i still prefer outside, but its a time-deal for me...