If you go to BTRFS, you'd better be running your NAS on an UPS. Otherwise you're going to be seeing "Error = parent transid verify failed" real soon.
Hint: If your file system is not set "read only" or "bricked" by the above error, you might need the following commands to resurrect it.
(If that doesn't work.)
I'd say, "Good Luck" but I don't really believe in it. Rather than rely on luck, perhaps you might consider looking at the BTRFS project page.
(This is what they'll admit to and it's been in roughly the same state for years.)
Why didn't I listennnnnnn!!!???