Just to correct myself and update on ztto 9-50 pro ult XD cassette.
It's not xdr, it's xd, obviously. Appologies. But since I'm here already, I'll just note that I had issues with rear wheel locking on the freehub with the XD freehub body for P3 Boost hubs from ZTTO. It simply wouldn't coast but pedals would turn as well. Good thing, however, is that I solved that problem by adding small shim over the axle, on the hub (sandwiched between freehub and hub itself. It's a small shim I dont even know where it was in the first place. I think I had it on my dt 350 rear hub that I have laying aroung.
Same p3 ztto hub wasn't having those issues with MS cassette/freehub.
Cassette itself isn't as smooth as Shimano. BUT, it does shift with acceptable precision. No too much unwanted noise. I still need to test it in driving conditions (i configured it on a bike stand for now) and will be reporting here. Bottom line: it can be configured pretty darn well, it is almost as light as XTR and it really does prevent chain from falling while back pedaling on 1st cog.
Im hoping it will serve me for couple of k's of km's happily