I don't envisage intercontinental touring on a Dahon. That would be taking enough time that I'd ride out from home. We took the folders for a weekend camping where the option would be a loooong day trip by train or hired car. The idea is sound to get round bike/train interface issues. As it stands, we would have had little or no problems with full sized bikes, but we needed guarantees of getting on the trains.
I do get frustrated with the lack of standardisation at Dahon, and finding parts is a nightmare. Even the couple of spokes we need to replace have proved to be an unusual size, and we'll be sourcing them via the interwebs.*
I also know that nobby and literida OTP have toured on folders (Dahon & Brompton respectively IIRC).
* Edit: Update. As we speak, Butterfly has informed me that a nice chap will cut down some longer spokes (he obviously has one of those cool benchtop tools for cutting & threading spokes