Yes, Moho Pro 12 can open and use ASP 9 files. In some cases, you may want to update ASP 9 file to take better advantage of Moho 12's features. However, once you do that, it might not be possible to go back to ASP 9 without losing those new capabilities. Generally, this shouldn't be a problem since it's not likely that you'll want to go back to 9 once you get the hang of using Moho 12. (I don't even like going back to ASP 11 anymore.)
Every version of ASP/Moho has it's own serial number and activation, so it's possible to run old versions concurrently with the new one. As a matter of fact, I still keep ASP 9.5 - 11 on my computer, along with Moho 12. This is mostly for testing purposes though...I don't use the earlier versions for actual animation anymore.
But it's probably a good idea to keep old versions available 'just in case'. For example, back when I was doing HLF on my laptop. I was using ASP 10 for that project and I discovered a serious performance problem with bone dynamics, and I had to switch back to 9.5 for just one scene. They eventualy fixed the problem in a later 10 or 11 update, but until then I was glad I kept 9.5 on-hand.
The downside was that this scene also relied on using Target bones, which HLF relied on heavily throughout the project, but this feature was introduced in ASP 10, thus not available in ASP 9.5. That made the scene more difficult to animate than it was in ASP 10. In the end, I felt bone dynamics performance was more critical for that scene, even if I had to create a ton more keyframes in the character. This is a good example of why I don't normally
want to go back to older versions of programs unless I really have to.
Anyway, I think you're going to be mostly pleased with Moho 12. The software has come a long, long way since version 9.
I want to know if I can use my old library content of Anime Studio Pro 9 in the Moho Pro 12 program. 
