First, I would love to hear your thoughts on that beast.
Second, I think the way those are split between 30mm high /90mm low,
it confirms my suspicion that the larger the driver is,
the less it is able to provide clarity at the high treble end.
Therefore, drivers rarely go above 50mm.
That's my theory for now.
It's also complementary to the Sennheiser employee's comments about stability.