Okay, interesting. Also to be clear I do think Z2 makes sense in a lot of situations, but I suspect that it's not very dependant on drive size like a lot of people think. If I wanted high reliability I'd use Z2 even with small drives.

Also to reply to your other comment: Personally one extra drive is a small price to pay for the peace of mind.

I achieve peace of mind via backups. For each copy, once I get the AFR below 2% I'm not too fussed about pushing it lower.