That depends on how you play, I humped part-way through UVHM using mostly a Bee, Unkempt Harold and Hawkeye, all at level 50, with Zer0. Around level 56 it got really, really hard so I finally moved on but up to that point it was actually ok, so if you had same-level versions you'd be ok. The trick is knowing when to stand back and snipe and when to charge in close, Zer0's action skill was a big help when it came to closing distances without dying since I had nothing to help me do much damage at mid range.
You're right, though, you can't exactly tank with a Bee, but that's not what it's for anyway. It's great for a glass cannon that can do huge damage until you get hit (at which point you pretty much die, so that only really works with a good Maya medic or Gaige with the Deathtrap shield recharge skill (or both) on the team, or if you're Krieg with the skill that fully replenishes your health in Buzz Axe Rampage or Salvador who also replenishes health when Gunzerking) or a sniper build where you want single, very high damage bullets that crit as often as possible.
