Hi, Maffblaster, I saw your edit and some things didn't feel right, so I would like to discuss them with you:

Are you certain that advising a risky but "safe" device removal by shutting down the system is wise? We are not saying that you have to have a redundant profile - basically if you do this on anything that isn't at least RAID1, you will lose data.
Are you sure that it is faster to remove a device this way? Your solution indeed mentions that you have to mount the fs in degraded mode, and indeed then you have to fix the fact that you removed a device by scrubbing the fs - isn't this what "btrfs de remove" will do gracefully anyway? In what way you save time?
It is worth mentioning what you do in case the device does fail and cannot be recovered - degraded mode (and a few other tricks) will certainly be needed to gain access to the fs again.
Since you also mentioned that the device could be replaced, it's probably high time that we introduce "btrfs de replace", which is definitely the fastest way to replace a device, with the "small" caveat of having to add the additional device to the fs in advance.

Let me know your thoughts - I'm happy to merge this info, but didn't want to do it without consulting first. Cheers!

User talk:Maffblaster