How low in bass do dipole surround speakers go?

In my limited experience, (ie, dipole surrounds vs bipole vs monopole), I found the dipole ones had a more immersive surround, with decent positioning between the speakers - tested with the Dark Knight, one of the iMAX scenes where a machine gun shoots a metal panel and it sounds like it pans behind you. Used a pair of 2.5" Sony widebands.

I suppose, in the end, a lot will depend on room placement. These were up against the same wall as the sofa, yet still managed to steer the effects behind you, regardless of listening position. To me, that's an ideal surround speaker. In free(er) space, I don't know if they'd do so well.

Dipole surrounds usually have one bass driver and two tweeters (or two mid-high drivers). The lower frequencies would be monopole, the higher ones would be dipole. In this case, bass to 80Hz can be expected.