IM will want to migrate the pbl, since the pbl is from an earlier version.
The import/export trick does work.
If you want to have a better idea what you can do by changing registry entries, take a look at this old PBDJ article I wrote for IM/PB 9: InfoMaker
Some of the hacks that worked in 9 (e.g. allowing you to write script in the IM Form painter) no longer work with newer versions.