If you're a procrastinator like us and you push your release back far enough that NS has already upgraded your Sandboxes to the new release before your Prod account, there's really no reason to not use a Sandbox for testing versus the RP environment, correct?

That's what we did 🙂 The scheduled upgrade for PROD conflicted with an important date, so we moved it. Sandbox was updated first, some of my key users already have sb access, same with integrations and tokens, odbc access, etc already in sandbox 1. So it made more sense to test in SB instead of RP.

We do both, as SBX has all the connections with our 3rd parties, so we test those there, everything else, we test using the RP. The other issue we discovered with this RP, is that some scripts and the ALA do not run, unless you schedule or run them manually.

Sounds like you haven't refreshed a sandbox for a good while - scheduled scripts/MR etc are unscheduled by default when you do a sandbox refresh now

Just refreshed a few weeks ago, just before the SBX upgrade. And yes, had to reconnect all 3rd party's and reschedule scripts