In terms of the bass management issues, while I consider the B&K's to be extensive, it is not 100% flexible. That is, one cannot choose the crossover frequency for each set of speakers (say, if one wanted 40hz for the fronts, 80hz, for the center, and 70 hz for the center). I doubt one would really need quite that much flexibility.
I'm in the position that my fronts are true full range, but tail off just a tad about 30 hz. My surrounds give up at around 70hz, so I have to settle on 70hz. If I choose to have the front signal sent to the sub then I get too much bloat (with both sub and fronts doubling up from 70 to 30hz). Therefore, all I'm really missing is the very bottom octave in my fronts, and most of that information is probably directed to the .1 channel anyway.
I've heard the ACT has a bass mgt upgrade that is extensive. Can one choose a separate x-over for each speaker with the Acurus?