Hi guys
I'll be able to answer your question since I work in Paris ACC (we're handling the ATN - BRY - CLM and UM733 routes for instance). If you work by the book, you HAVE to say "Airline 123 bonjour, maintain FL360, route ATN, CLM".
Now, practically, I think it's useless if you already said your route and cleared level on first contact, therefore I'd just say "identified" in your case. (by the way, is the word identified OK with you?). As you said, it caused unnecessary freq occupation, and when there's just too much traffic we just say "identified" ;-)