Thank you, Unionman, for a very interesting post.
This is a joint application for both the Hibbert Road and Buxton Lane developments and ASDA would obviously have a considerable interest in the prompt and efficient completion of the Buxton Lane site since they would be unable to start their own development until Buxton Lane is completed, something which I think I have seen confirmed elsewhere on this forum. You are probably right about a lack of necessary experience within CAMSFC, although plenty of professional experience is always available at a price, and in view of this, I would have thought it quite likely that ASDA might well manage the Buxton Lane development themselves, using their own project management resources both internal and external. They must have huge development experience available to them.
I don't agree that the proposed development would "drastically" alter what is, in reality, a suburban dormitory town. The size of the development seems large enough to meet the needs of Marple people but not so large that it would attract many others from outside the area, given that there are larger Asda at Stockport (4m) and Hyde (4m), plus large Tesco at Stockport (4m) and Hattersley (7m), Morrisons at Bredbury (4m) and Sainsbury at Hazel Grove (4m), not to mention Aldi at Romiley (3m) and Waitrose at Poynton (7m). What it may well do, however, is persuade what I suspect is the the great majority of Marple people who travel out of the town every week to shop locally, perhaps buying their hardware, DIY materials, toys, outdoor gear, and many other products in Marple instead of making what are, at the moment, very short detours from their favoured supermarket to B&Q, Argos, Toys R Us, Homebase, etc, etc.