2 areas of enquiry:

How easy do you envisage it being for to swap the board into an almost working n900? What tools would be required? Would it be a slot- and screw-in job or would it require soldering?

We have had mention of one of the common hw weaknesses in the n900, the usb port, but not of the other, the SIM issue ? Is an n900 that has developed this likely to be a good candidate to upgrade? I can't quite work out whether the existing SIM housing is used for the new kit.