It appears to use a lot of memory because it replaces the standard kernel disk cache with its own ARC, and as unused memory is wasted memory, the ARC will eat up every last bit of memory you allow it.
Well, I had 4GB of RAM, the cache ate up every bit of it and didn't run particularly well.
It's performing a checksum of your entire system. That's going to be a CPU hog. BTRFS will be no different in this regard.
Very true, but if CPU usage is a factor, on an app server say, then choosing ZFS is hardly a "no-brainer" as the OP stated.
Of course it does. It just has some limitations.
Right - what I was looking for is the ability to simply add a drive to a pool and get more drive space. With btrfs RAID1, which is what I'm using, you throw a drive in, hit rebalance, and you now have more storage, properly mirrored with distributed metadata.