osJoe
I'll answer this one extra bit here, if there's something else related to your install it's probably best we move to a different thread, this one is already getting mixed up with information.
User created files are basicly stored in the following locations:
~/Movies/Motion Templates (FCPX titles, Generators, Effects, Transitions)
~/Library/Application Support/Motion/Library/ - This everything else, like when you customize a behavior or layer and then drag it to the library.
Deleting the application (drag and drop to the trash) does not touch these other files. If you do want to be extra safe, you could back up the directories above as well as Motion 5.1.2 Just compress them in a .zip files. Again, just delete Motion from the application folder and then empty the trash before you try to re-install from the app store.