No time like the present. With the latest version of NA ... Note that the NI forum thread linked above specifies UNinstalled. Apparently updates have changed that.
I moved my Form and Flesh folders to a different drive. Then I launched NA, selected INSTALLED and noted that both showed errors. Clicking Repair, then Relocate, I was able to browse to the new location and everything worx great.
Moving back was also painless. I'm quite relieved that I'll be able to recover these from backups instead of spending 11 mos downloading again. If my Samples drive dies ...