There is a price to be paid (as in tradeoffs) for all of the different methods of designing and building speakers. "Sealed box bass" (acoustic suspension by another name) is high-pressure bass meaning that every time you have a rarefaction of the speaker cone you are pressurizing the inside of the speaker cabinet with no place for the pressure to escape except where it tries to leak back through the speaker cone. You also pay a price in efficiency of the speaker which then requires amplifiers with high output power to be used. In other words, there is no free lunch and there is no single 'right way' to design and build a speaker.
Yes, that's the theory. But recently, some manufacturers were somehow able to overcome a lot of these obstacles. EA's MM3 has incredible bass, tweakable too, but they're helped by the internal power amp. YG's earlier models indeed suffered from the "monster amp required" malaise, but the recent models are far more efficient. And of course, the Magicos (post Q5) are quite efficient, sometimes more so than ported speakers at the same price range.
mep, have you heard any of these recent sealed box designs?
alexandre