Mousy, I dont think you need to be too concerned about the loss of the qualities you list. Nankins have never made any great claims to be ' useful' utility fowl, and although our UK stocks do have a tendency to be over-sized, we're not looking at such a massive reduction of size to challenge the birds current capabilities.
if we take an average true bantam size from breeds such as the Rosecomb, Sebright and the Dutch, three breeds that bear a resemblence to Nankins in terms of type and posessing the size we are aiming for, we find that these breeds still give a reasonable account of themselves as layers for 'toy' varieties, and although Nankins are regularly referred to as sitters, given their size, i doubt they would ever be of great use as broodies.
Egg flavour is not something I know much about, but wouldnt this be as much a factor of nurture rather than nature? A good varied and natural diet must go some way to creating that 'traditional' free-range taste??
I certainly can't imagine a Nankin has ever have been or will be a worthwhile table fowl subject. Surplus males might be used up in the curry pot, but as sunday Roasters they wouldnt be in the running!!

I can understand your reticence over cross breeding to achieve your aims from a dog breeders point of view, but it's been common practice in the poultry fancy since the concept of a chicken being of a ' breed' was conceived. Even today, breeders are improving or creating new colours within breeds by the inclusion of different breeds that carry a desired feature into their chosen variety.
Most breeds are composites of a number of varieties as it is, and with poultry being far more easily and quickly reproduced than dogs, and in far greater numbers, which provides a larger choice of genetic permutations to select from, results can be achieved far more quickly.
As an example,I recall talking to a fancier friend at the PCGB National show in the early nineties, who took show champion with a spectacular white cochin cock. After all the applause, trophies, rosettes and congratulations, he led me to the Brahma classes ,( his first breed ) , and showed me his champion Non standard, Large White male, that was half brother to the Cochin show champ!!
Mousy youre right! it was Brian Sands that recreated the rose combed Nankin, not Andrew sheppey! D'OH!! don't tell them i got them mixed up!!!
