story
As long as you don't do BTRFS-level raid 5/6. (Just do lvm-level or md-raid-level raid 5/6) don't do many subvolume with quota. (many subvolumes is fine) It's production ready.
I don't know where this "btrfs is not stable" coming from. According to HackerNews, I should have lost my data due to BTRFS 10 times already.