I’ve been running a XCR USE post on various bikes for the last 2 decades. Currently a SUMO head version on my mk1 solaris.
they are good for what you want them to do. there’s lots of talk of the saddle height dip when it sags etc, but it just depends on how you set it up. Like in the review, it can be set to sag a mm, and take out most but not all of the chatter, or sag a little more and really smooth things out.
The point is IME, and I’m very saddle height sensitive, you dont notivce the drop in saddle height when riding bumps, as the bike comes up to meet you anyway.
I recall USE had a good run ‘hiring to buy’ at the mountain mayhem at sandwell many years ago after fatigued bodies realised the benefits of a suss post riding the ploughed field of doom.