According to the store page it’s possible to buy a Unity Pro license with the non-Pro iOS add-on. What happens if you have that combination license? Does it just disable all Pro features when working on an iOS-enabled project, or do you get access to some of the Pro features? I was thinking it might allow you to use the build-time Pro features like global illumination baking and external VCS, but not the runtime features like RTT and occlusion culling and such, but that’s just a guess.
You can’t switch the project to iOS. You have to switch licenses to do platform switching. It is possible to bake GI and then switch; that is probably the only worthwhile thing you can do with that license combination.
There isn’t quite such a thing as an “iOS-enabled project”. A Unity project is pretty much just a Unity project. Yes, if you switch the platform to iOS, it will re-import some assets (such as textures) to an iOS-compatible format, but loading that project onto a computer with a desktop-only Unity license will just re-import those assets back to a desktop-compatible format again. (The same thing that happens when manually switching the build platform back to PC/Mac.)
Anyway, I don’t know for 100% sure, but I’d be really surprised if your guess is not the case. It seems unlikely they’d go out of their way to turn off all Unity Pro features when switching the build platform to iOS…that would be bizarre and inconsistent. The GUI skin for example–if you had it set to the Pro-only dark skin, would it switch back to the light skin when switching the build platform? I seriously doubt it.