The magnet structure (both field coil and Alnico variants) and cone profile of your Supravox is, IMO, a work of art, and should be in a league of it's own in terms of control and transient response vs more "conventional" drivers. You are using it exactly as intended, as the driver is designed for such cabinets, can't go wrong with that approach
18sound released some very interesting drivers, all well suited to TQWT. The novel feature is something they call "AIC", which basically is a second voice coil counteracting the driver's impedance peak, as such, driver impedance is completely flat without needing to use crossover parts. Of course, cone and magnet are not Supravox level, but super interesting, intelligent feature IMO.