Just throwing out our experience here. Probably not worth much without some additional info, but after fighting for 4 days I feel like sharing regardless.
We have an SoBR with 200TB+ of usable storage spread across 7 physical servers and 12 extents (we try not to have our ReFS volumes be larger than 20TB, because of issues in the past). Of these 7 servers, 6 have had their performance improved after the update. We updated because we were having issues with one of the server's performance. This server having issues is actually identical hardware-wise with one of the others in the SoBR, but it TANKED after the update. Would become unstable after ~2 hours of running small backups. Seems like a warning sign for these ReFS issues is an ever-growing value for "Modified" RAM (not sure if that was mentioned in this thread already).
Anyway, Modified RAM would go higher and higher, then RPC / WMI would start failing on the repo (same old story throughout this thread). You'll notice the graph actually started going down, this is because around 2am the majority of our jobs were outright failed and past the 3 retries, so operations were mostly stopped on the offender, rs-bkptar-1.
Just replaced the newest refs.sys with refs.sys version 2097 on that single server and the server is now rock solid. Catching up from the failed backups last night at record pace. Before, we were seeing disk response times measured in seconds, now everthing is sitting pretty at <50ms. Running more concurrent jobs than we were when it would slow to a crawl.
I don't quite understand how refs.sys can be interchangeable like this, but I really hope it doesn't cause some silent corruption that pops up 3 weeks from now...