Just a couple of comments:
I did work very hard to get my first amp and it was giggable, and I took it to every gig, even when I knew there'd be a better amp to borrow. I would ask nicely and usually borrow the better gear, and I really appreciated it.
I've "shared" my rig at a few gigs, and normally it goes OK, but i've had a couple of guys who seemed really nice, and looked like they were listening to me, and then went and wacked up the low shelf or similar. With my Peavey POS that can put it out of action for an hour or so as it calms down. Some guys just don't seem to care.
I've been playing drums lately. Sharing shells does save a good 5-10 minutes, but, I get nervous sharing my own becuase I know I can't afford to re-skin it (no matter how cheap some of you think skins are).