I know that it isn't possible to use a protected UID and Open Signed Online but what about the offline version??
I tried to programs each of them using a protected UID. I signed both using open signed offline but then it didn't work as I expected it to. I could install the first app but when I try to start it it gives me "System Error". When I change the UID back to an unprotected one it works flawless.
With the other app I didn't even get so far, as when I try to install it I get an "Actualization Error".
I just figured out, why the actualization error occurs. It's because the old app can't be overwriten by the new one when UID differs. So you have to delete the old one manually first.