Sorry if answering your own question is a protocol violation but I found the following thanks to Google and thought others here might be interested: http://translate.google.com/translat...26prmd%3Dimvns

This looks like a useful list. Note for example 2012: ‘The World Birdy models are produced consistently for the whole world, to save costs. The equipment and the color are given, there are limited options available from the factory. The frame is similar to the classical framework. Auffällgster difference: The main tube is rectangular.’
And in 2010: ‘A Birdy without disc brakes can not be easily retrofitted, because the disc brake models have special wings, which does not exist as a single part.’

Never-the-less, assuming the new frame is at least as good as the existing monocoque (?) it still seems to be a good idea to follow jur’s advice proposed earlier on this thread – buy the basic model and upgrade components to suit individual needs. Note that there is a 2.5 X price difference between the World Sport and a Speed or Race Disc – and > 3 X for a Rohloff model (could find several good retrofit components for £2K even in the UK). I am strongly tempted.