Sorry, only just noticed this reply! - my apologies.

I've actually taken the next step now and gone ahead with the full geared conversion, similar to your own schocca.
I've used mainly 9 speed sora RD/shifters/gears - fsa crankset and the cyclocross FD (10 speed top pull).

Only issue I'm having is with the bottom bracket. Did you change the stock bottom bracket on the dahon?

It would appear the spindle length on mine is too long for the FSA crankset, the FD cage doesn't swing out enough, even with limit screw fully out.

Any suggestions on the correct BB to use?