Does btrfs still eat your data if you try to use its included RAID featureset? Does it still break in a major way if you're close to running out of disk space? What I'm seeing is that most major Linux distributions still default to non-btrfs options for their default install, generally ext4.

Anecdotal but btrfs is the only filesystem I've lost data with (and it wasn't in a RAID configuration). That combined with the btrfs tools being the most aggressively bad management utilities out there* ensure that I'm staying with ext4/xfs/zfs for now.

*Coming from the extremely well thought out and documented zfs utilities to btrfs will have you wondering wtf fairly frequently while you learn your way around.