My experience is that you cannot stop developers doing goofy stuff in the transport layer with your XML - kinda case of all uses are "good" uses anyway!
Just have to learn to live with it and be pragmatic - advise people that it may not be appropriate for all live use cases. RSS server delivery does of course have other cool features - like being able to check when and if someone has actually picked up the package you sent them and provide password access control. So things that are in DE itself may be delivered by proxy by an RSS server even if the ATOM packaging does not appear to provide that directly.
Thanks, DW