If you could afford them, the M&K 150s would kick some serious butt! I've heard them before and for movies it's a very impressive set-up. Like most speakers, M&K's do sound the best when you're in the sweet spot. However, they do have very good off-axis response also. It's mostly because of the crossover they use and the dispersion pattern of the speakers themselves.

Think about this one. You could get a decent, small subwoofer to provide nice bass for the system. M&K, Sunfire, plus many others make subs that, while not neccesarily shaking the room, they do provide a nice solid bass response. Then, you could add a tactile sound transducer for under your seating and presto, earth-shaking bass that you can't tell where it's coming from.