Neither the chest up by the top of the waterfall nor the red chest in the little room below the waterfall will respawn unless you save and quit. Pulled a Nasty Surprise out of the red chest a few days ago.
I got a Fastball grenade out of that red chest once in TVHM as well as 3 different E-Tech Dart pistols from that chest, but never anything good from BNK-3R himself, so my preferred method is Save & Quit & Reload. . --- What's the purpose in owning a Grenade Launcher? The sheer inability to continue life without it ! ! !
id say restart simply for the chests. ive gotten quite a few orange items from the red chest as well as a ton of etechs. it helps to slightly increase the value of the loot haul. --- Crazy? Crazy with low prices on Wind Brahmin. You buy one!!
It's pathetic that the red chest gives you better loot than BNK-3R does, he's always been a cheap bastard. . --- What's the purpose in owning a Grenade Launcher? The sheer inability to continue life without it ! ! !