I expect (hope!) Apple will have worked hard to get the most out of the processor in terms of power, cooling and minimising throttling, so we probably have the best chance of seeing what coreM can actually do in these new machines. It's encouraging that in the buy to order GPU model they seem to have actually overvolted it to give a base frequency 0.1GHz HIGHER than the advertised base frequency of the top of the range coreM (the M-5Y71). That's actually allowed for in the specs for that processor, and seems to mean that it will be running closer to 6W than the 4.5W nominal TDP, which also is encouraging as it suggests they have done the opposite of the first laptops using these processors that limited the TDP to around 3W instead of the nominal 4.5W...
Can't wait for the first tests, as a well designed chassis which this seems to be should let the M-5Y71 do its thing as well as possible, and that might allow results close to if not as good as the i5s and i7s of older generation MBAs etc.