In the end I just exported contacts from the gui. There was an error when I tried it with vcard 3, but 2 worked fine, although I got a bunch of unknown blank contacts, a couple with facebook profile pics

It's interesting comparing the two devices. The HTC is a far superior phone (I've been suffering from n900 problems with auto rotate and answering/ending calls, plus missing SMS and missed call notifications due to unnoticed screen freezes), but the n900 is the only one that's really a computer, plus the hardware keyboard makes a big difference for me