Ha LOL yeah I started off with Pro Audio 9, so I know where you're coming from - I have a habit of not "updating" stuff until I really have to - why fix it if it ain't broke - but then it all sometimes comes unstuck at the last minute.
OK, so, just for my clarity, if I understand correctly (other the the X1 to X1 Expanded scenario you described), these upgrades are not really "upgrades" to a base product, they're really a full install with a "price discount for product loyalty", and there are limited "hard" dependencies on the version that's currently installed.
Woohoo, if that's the case, I'll be doing some downloading soon
Cheers ... Kimbo