As far as I understand Wendell has been so dogmatically against dynamic driver cone bass for so long I wonder if this development opens the psychological and design doors to other very interesting product possibilities, such as woofer tower options for full-size models.
Yep, he says he's never heard a hybrid that had the realism of planar bass. I think what changed here was the technology. A sealed or ported woofer has an omnidirectional radiation pattern and excites more room modes than a dipole.
A dynamic dipole woofer doesn't suffer from these issues, but there were still quite a few challenges to solve. DSP solved the problem of dipole equalization, and they were able to develop a configuration that's both compact and blends well with the planar panels, but it took a lot to get there, something like two years of experimentation with designs, drivers, etc.
I think your comment about psychology is astute, though Magnepan's concern here was with customers, dealers, and the press! According to Wendell, hybrids have a bad name and there was resistance to a Magnepan hybrid. He concluded that an incremental approach was best -- rather than developing a hybrid using this technology, they would develop an active dynamic dipole woofer that could be used not only with the 30.7 mid-tweet panels and midbass coupler, but with other planars in their line and that was small enough to be hidden behind furniture or a couch. Hybrids and larger woofers could be developed later if this incremental concept gained traction.
I'd love to see a larger dipole woofer with greater extension and enough output for large spaces. I've read that this woofer has extension down to 10 Hz., but it isn't flat to 20, though I imagine you could stack them for use in a larger room. (Really, I think they should also offer a sealed Magnepan sub for those who listen primarily to rock and prefer slam to accuracy, but it's hard to convince Wendell of that, since their focus is on naturalism -- and, really, there are quite a few excellent subs now for those who want to go that route.)
Meanwhile, someone who wants more bass extension in a dipole could buy the GR dipole drivers and plate amps, though those are still a DIY product in that you have to make the baffle yourself.
Anyway, they're dipping the toes in the water here and if the concept is accepted, I think we'll see more variations.