"Interface to User Logic" vs "User Component"

Think of Interface to User Logic being a subset of features present in Component Editor. You don't have anything to gain by using Interface to User Logic (that I can think of anyway) so I would use Component Editor simply for that reason. As for the exporting feature, it is present.

I often build components outside of SOPC Builder top level first so that I can stick to the same SOPC generated system and just modify the component by itself (just a force of habit). Now days in order to do this I click the menu option that creates a generic list of signals that is common in most components making this a one button process (just like what you want to use Interface to User Logic for).

I hope that helps explain why I think most people really don't have a need for Interface to User Logic. Besides if some really great feature comes down the pipe for Component Editor I wouldn't hold your breath to see it in Interface to User Logic.