In which cases I should forbid the users to move my app to the SD Card (by setting installLocation to internalOnly)?
I'm asking to know this for a few apps, so please don't ask about my app. I want to know this in general for any app.
The requirements is quite well described in the documentation. Primarily, if you're running anything in the background that must execute at all times, like a service, or if you provide widgets, you can run from external storage. But as soon as the user unmount the external storage, the process in which these things run will be terminated.