Seeing this thread due to the bump.
On that driver, they mentioned a while back that the ability to cheaply/rapidly iterate the bracing structure via 3D printing was essential to satisfactory progress. Previously, they've managed to make a cone tweeter with rather low distortion, and get good sonics via clever use of somewhat novel but relatively prosaic materials elsewhere in their speaker and cabinet implementation, so I expect they have a more than even chance of making things work.
In other words, much of what
@617 says. It's not a wide-bandwidth driver though, but they did mention excellent dispersion.
Their cabinets use MDF, a plastic honeycomb laminate, open-cell ceramic foam, flexible elastomer and glass for different mechanical and acoustic properties. The glass is part of the mixed mass damping, it doesn't hum.
They also use different materials to construct and mount the drivers, like two part plastic and aluminium baskets to damp resonances, pre-tensioning of the aluminium cones to shift resonance/breakup well out of each driver's audio band, damped mounting of drivers to chassis and so on. The current series drivers are all spider-less. Diestertich's thing appears to come from a materials engineering background. It is very German and pragmatic, the materials are used for their intrinsic properties and useful application, not because they are gratuitously exotic, I like their approach too.