I got the impression somewhere that btrfs RAID 5/6 support allows, or will allow, new devices to be added to an existing RAID group.
That's an important feature for home and small business users. Having to replace every drive in a RAID group to grow it, as ZFS requires, is painful and expensive.
Fortunately, drives are cheap enough these days that you can just way oversize your pool to begin with. But anyone switching to ZFS should be aware of the need to do this.
You can add/delete devices from raid5/6 volumes now. The raid5/6 code is still experimental, in particular while detected problems are fixed on-the-fly to userspace, the fixes aren't written back to drives. That limitation applies to normal usage and scrubbing. A balance detects and fixes these.
Also the determination of a drive being "faulty" (in the md/mdadm sense) and how this gets communicated to userspace isn't in place. If it's in place for ZoL (?) that'd be a considerable difference, a bigger one than checksum algorithms in my opinion.
Can you link to anything about oversizing the pool? I think I vaguely remember a trick with creating a sparse file and adding that to the pool until you can replace that with a drive.
That's an important feature for home and small business users. Having to replace every drive in a RAID group to grow it, as ZFS requires, is painful and expensive.
Fortunately, drives are cheap enough these days that you can just way oversize your pool to begin with. But anyone switching to ZFS should be aware of the need to do this.