I've got one on a 300blk 8.5" with the silent capture spring.
Overpriced but looks good and comfortable. It is compact. It is not particularly light.
I did mortar the gun a couple of times (stock fully retracted) with some overly long cast lead bullets to dislodge them. This very slightly bent a part of the release mechanism, but I bent it back. The lockup is solid. Adjustment stops are very positive.
I have the extra sling plate on the bottom. In fact I have a spare for some reason so if someone wants it, PM me and if you cover shipping you can have it. I'm not convinced it's any better than putting it on the already extant qd slots, unless you're trying to maintain ambidextrous capability.
The older style buffer and castle nut was very hard to tighten appropriately without damaging the finish. It does not appear to be a problem on the new design. A little road rash doesn't bother me too much, though.
No complaints overall other than the price, but its what I wanted.
Since efile came back online I considered sbr'ing the gun but the actual stock looks kinda dumb tbh.
I'm only talking about the brace itself if that wasn't obvious enough, the gun listed looks overpriced as fuck.