Well, keep in mind that language has remained unchanged for a few years now. Certainly BcacheFS has some theoretical advantages (lack of write hole etc.) but B

Well, keep in mind that language has remained unchanged for a few years now. Certainly BcacheFS has some theoretical advantages (lack of write hole etc.) but BTRFS has nonetheless improved since then and BcacheFS has gotten more complex. It's still a very exciting filesystem so I'm sure we'll be seeing third parties test it rigorously very soon.