Ugh, I'm in a catch 22! I went to go after BNK-3R, and I quickly realized that I was out-leveled quite a bit when a Bull Loader was one level above me. That meant that BNK-3R would probably be three levels above me, which isn't good... at all. Normally when this happens, I drop back to where I was before, and level up a bit. What's wrong with that? Well, "where I was before" is Opportunity, and my game freezes after about an hour to an hour and a half into the zone. :\ It's a real buzzkill on a Mechromancer, because you really need those stacks, and having to kill the game will remove all of your stacks.
I'll just have to put up with it or see if randomly leaving about an hour into it will help. Oh, and I have found that using my explosive rocket launcher (~50k damage) against a Super Badass Loader with 200+ stacks of Anarchy is rather amusing. It takes about a third of his health each time, and it's one of those rocket launchers that uses less ammo and has a large magazine (7).
I also have to say there are a lot of cheap ways to die in this game, such as those suicide bots and enemies that seem to suddenly spawn right on top of you. I have been playing solo, and I think the game is really focused more on co-op.
I definitely agree that the game seems to be focused more on co-op. Some situations are much, much easier if you can use everyone's strengths to help another character's weakness. For example, any other toon could help with long-distance targets, which is where my Mechromancer fails... big time.