I’ve just bought a Praxis because I’m not that impressed by expander rings either – it’s mainly the jump where the 17 is missing that pisses me off because the Dyna-sys seems to struggle with it going up, and also missing a much needed top on these newer systems with more limited gear ranges.
Mine won’t get fitted until the current transmission wears out tho, so I can’t really help other than to say that I have known a couple of cases where relatively new Sunrace cassettes were believed to be the cause of shifting problems in the workshop I was working in two years ago. That was 8 speed Sunrace tho, and it wasn’t part of any scientific survey…it was just mystery problems that went away when we swapped out the cassettes and put shimano on.