There’s always a next-great thing. In the case of fast transistors, cool. Show me an audible benefit that everyone can hear before I get that hyped up about it.
It’s what the present Class-D "cons" are all about, listen to a SE-R1.
I’d lay money on it, that you’ll put one of the first with your hand up for one when it suits your pocket.
And your old one with the lower switching frequency, will become unsellable junk save for use as a bass amp.
Cheers George