Heh. Yeah, there's a lot that can make it safer but... frankly, I've been bloody one-shot by critters coming out of those vaults in the early game. On easier
, which translates into 30+% overkill on anything else, heh. With con-focused, high HP combos. S'only so much you can do when the opening round from outside your LoS is a 2-300 damage instapop.
I see those vaults as potentially helpful, at times, but fundamentally when you open them, you're putting your head into the RNG's hands more than just about anything else you can do in the ID. Teleport only does so much when something with a global speed boost/movement infusion/etc. that's 30+ levels above you (and possibly elite and/or rare and/or equipped with voratun weapons) comes out of the shadows and stuns you, locking said teleport down (assuming you survive the hit at all
So yeah, when I run ID I've just stopped messing with vaults until I have a good 300+ effective HP at minimum and, preferably, something like a psychoport torque. There's nasty things hiding in those vaults. For someone unused to the ID or T4 in general, I'd imagine "avoid the vaults" is likely one of the best life-extending decisions they can make