Yeah, its pretty tough, have you cleared it? My friend had tried it a few times, and struggled with people fainting. The run we cleared it, my friend actually fainted before the SOS crew even loaded in and wanted to restart, but I said screw it lets just see what happens / get some practice. I think its harder fight for the melee guys (due to the glowing haemorrhoids haha), but for bow you can keep a bit of distance and he has so many crit spots.
Well played, I hardly ever solo, prefer the aggro split of 4 player. As for end game, yes it seems to be working through challenges to keep ranking up e.g. HR50 is Tempered Elders. Also the grind for decent decorations and weapon augment is real, I think I've got maybe 5 useful decos out of ~100 drops so far.