WOW, that’s a lot.
Might help with signature link. I had to guess and play around to figure out how to do the ‘hidden’ thing. Forum Suggestions - #110 by Davvo
I think you stand the same chances of the second drive in the degraded mirror no matter what you do. All three methods have the drive reading and writing, moving data around.
It might help looking at the drive / pool data from Calomel. Test is old but it give a general idea of drives, pool configurations and performance. ZFS Raidz Performance, Capacity and Integrity Comparison @ Calomel.org