The G-Side show at DC9 last year was phenomenal, as was Ardemus' opening set. It's the kind of show I wish people who think live hip-hop sucks could have seen because everything about it was right on.
For the most part, I think people who say live hip-hop sucks just dont' really like hip-hop that much. A rap show can be just as good and exciting as any rock band. Plenty of rock bands have to deal with shitty sound but who cares because it's awesome and it roars.
Jay Reatard's set on the backstage at BC sounded like mud, but it was incredible because they rocked the fuck out. Odd Future's set at U St had the acoustics of a jackhammer but it didn't matter because it was exciting as hell. You're not going to get the fidelity of some hippie and an acoustic singing about his period and that's fine with me. Some rap artists/bands can bring it live, some can't. No different from any genre.
Meanwhile I can't tell you how excited I am about seeing Killer Mike and Mr. Motherfuckin Exquire (opening for El-P) in July.