Subwoofer options for Magnepan with crossover betwen pre and amp?

Brian's quite a guy. Danny too. Brian found the OB/Dipole sub to be too lean sounding, without the weight he expects from a sub. But that leanness is one reason it works so well with dipole speakers. And their dipole figure-of-8 radiation characteristic matches that of dipole speakers, one reason for that leanness. OB's excite fewer room modes than do omnipoles, resulting in less "room boom", the "overhang" in bass notes some people blame on subs when the real cause is the room itself. Without the low bass reproduced by a sub, the room won't have it's lowest modes excited by the loudspeaker (which doesn't produce very low bass), hence the room's ability and tendency to boom remains unrealized. Add a sub, and that ability and tendency becomes apparent and audible. Fat, "slow" bass (overhang) is always blamed on the sub itself, whether justified or not. 

I'm about to set up both my OB/Dipoles and Magneplanar Tympani T-IV's in my new room---I'm interested to see the similarities and differences between the OB sub and the T-IV bass panels.