Handle changed Elevated Trust installations better
It seems in SL4 that if you are running a NON-elevated trust program and then decide to enable Elevated Trust you isolate all your existing OOB installs out there as the update mechanism will not download it.
I think a simple solution is the same "This program requires Elevate Trust" installation message when you try to update an existing non-elevated trust program with a new version that now requires it.
Instead, I have to basically loose all my OOB users and ask them to uninstall and reinstall the new version, just because I decided to elevate it. You don't always know that you will need Elevated Trust when you start development and you'll just lose users/orphan OOB installs with the current method.