I played around in IS myself, keeping our discussion here in mind.
I think the reason my NT can do so well in there is due to the fact that her absorbs are actually strong enough to matter against their attacks. Because of that, it would actually be possible for her to solo Hezzak, Inobak, and Dominus at the same time.
But, everywhere else, they really aren't. My 60 can't insta-cast them at full def, even with maxed nano init, and a pretty high level compiler. I could go out of full def, but the absorbs don't take a full hit from the things she would need to spam them to survive anyway. It's a similar story at 220. The bigger baddies punch clean through our absorbs in one hit. Add to that, Looping Service is really nice, in that it casts an absorb for you via proc, but it still overwrites Superior Fleeting Immunity. It can actually be extremely bad, instead of helpful, depending on when it decides to go off.
Absorbs are definitely a weak link, across the board.