Save Learned Midi info?

have to have 8 installed along with 9 (since they are basically incompatible.)

No they are not.

Controller assignments are flaky, for a number of reasons. You should be backing up your control surface preference file (these contain your assignments). When it goes kaplooey, qui Logic, copy over the pref file from your known good backup and restart.

You can also lock your cs pref file to save Logic overwriting it.

/Users/ YOU/Library/Preferences/com.apple.logic.pro.cs

They warned me that opening any song created in Logic 8 with Logic 9 would more than likely have problems

Page 163 of the manual:

"Opening Projects from Earlier Logic Pro Versions
You can open Logic Pro 5, Logic Pro 6, Logic Pro 7, and Logic Pro 8 projects in Logic Pro 9. When loading a project created in an earlier version of Logic Pro, the format is converted to the version 9 format."

LP9 is not "incompatible" with LP8 projects. LP8 can even, with some limitations, load LP9 projects (although obviously without LP9-specific features).

However, in general, largely because of bugs or poor handling, it's not recommended to really work with projects from earlier versions. In theory, in should be fine, and I've only rarely had problems working on previous project versions, but it can lead to oddness, corruption, or weird behaviour. This is not due to incompatibilities, but simply bad project handling in Logic.

The technician explained that they would never support Logic 8 songs properly in 9 therefore made it so you could install both versions simultaneously.

Sounds to me he doesn't know what he is talking about, or is generalising. The reason updates leave earlier versions is for various incompatibility and production readiness reasons.

He actually really sounded like he knew what he was talking about quite intimately and he provided great tech support.

Cool.

But because the program architecture is so vastly different it simply is not recommended.

Well, not recommended is the word on the street, yes. But this is not an "incompatibility", it's issues with Logic's project handling itself. It's simply too easy to get corrupted projects, and this is a flaw in Logic. If the song formats were designed/changed to be incompatible, LP9 simply wouldn't let you load earlier project versions - which would be clearly undesirable.

There are too many (and this was his word:) incompatibilities.

Yes, and I expect that word was chosen very deliberately, because it's a corporate policy to not admit flaws in the software. Therefore it's more politic to say there are incompatibilities rather than suggest flaws.

But yes, as I say, there are indeed issues with LP9 working with earlier version songs which can manifest themselves in some circumstances.

but just because it says you can open songs in the manual doesn't mean they are going to work out.

Sure. But if it's an official, documented feature that doesn't work properly in some situations would suggest that this is more along the lines of buggy handling, rather than a designed in intentional incompatibility or change in the song format that cannot be effectively accomodated.

Anyway, not going to devolve into an argument over semantics, so... 🙂