The upgrade from RHL 8 to RHL 9 went off without a hitch. (privately amazing me to no end)
Hit a minor brick wall when I went to up2date the installed packages with their security and bugfix components from the redhat network. Apparently the shipping version of rpm with Red Hat 9 has a bug that causes rpm to hang. Red Hat themselves have not released an errata update for rpm, however bugzilla.redhat.com details a way to upgrade rpm to the current 4.2.1 release from rpm.org, after which, the additional upgrades went fine.
After this, I went in and re-compiled and installed my additional apps, and with the help of my modulereport script, upgraded all my relevant perl modules.
Then, I took a three-day vacation to the beach, and left the 'puter in the hands of my (mostly) non-computer literate roommates, figuring if there were going to be any problems, they would find 'em... and nothing. <grin> So, all's well that ends well.