Three Single drive Raid 1 vs JBOD

Solution 1:

Is there some performance or other drawback to this VS creating a real JBOD on a controller that provides the option?

Likely not, but that depends on the actual controller at hand. RAID1 with just a single disk implies that there's a missing disk, so RAID0 would be more fitting by logic alone.

You should be aware that you're running that controller outside its normal operational envelope - somewhat unlikely but theoretically possible there could be performance issues but also logic problems like overspilling event logs. In any case, test well.

Preferably, look for a controller that explicit supports what you're doing and possibly consider a simple non-RAID SAS or SATA HBA.