Hmm, I have a friend that used a choc bays as a changing bag but two kids later I would not use an M bag as a changing bag, the risk of spills and damage is just to big.
Actually, come to think of it I have seen lots of people here using the Mulberry troutbag as a changing bag... Not sure if its available in the UK now (if that's where you are located), heard they were continued to be produced especially for the Scandi market as its such a popular bag here. Not sure I've seen them in store here lately either come to think of it, but that would be absolutely perfect as a changing bag if you want a Mulberry.