One is a 644DS (the one I use most) and the spare is a CCM 644 Flat Tracker that is on a limited registratiion (cannot be registered by anyone else within the EU). I´d have to bring it back to the UK in the event. I suppose I´d have the same situation if I attempted to import a Spitfire!
I´ve owned a 604 and appreciate the ability to do what you want with the engine. That is one of the main reasons that I´m hanging on to the 644.
What part of the country are you in? (I´m in Berlin)