I have Time Machine configured as SoftRAID 1. I am contemplating clean installing Monterey. How best to handle SoftRAID? Uninstall, or just unlicense? Once I've installed Monterey and SoftRAID and licensed the latter, will it recognize the SoftRAID volumes that I created under Mojave?
Yes the volumes will be recognized.
However, this is a good time to start with a fresh volume for Time Machine. Time Machine requires APFS for Monterey. It does work on inherited volumes, usually, but if there is any glitch it will stop working.
Thanks for the response. Good idea.
Another question. Should I unlicense SoftRAID on the machine before wiping the boot disk? Should I maybe uninstall (delete) it ... or both?
You can ignore it with 6.2.1.
I was mostly referring to starting fresh with Time Machine, but the OS is not a bad idea, its good to clear out the detritus once in a while.

