My experience is that the inletting on McMillans are more precise, the stock has far less flex in the forearm, and it typically has a higher strength-to-weight ratio (subjective, I know). You can get it in virtually every possible configuration (and every color combination). The B&C is a $150-200 stock, and the McMillan is a $450-500 stock.
McMillan will also take your rifle and bed your stock to the gun. At this they do a jam-up job. B&C and HS, in my experience, will tell you that bedding is unnecessary and even voids the warranty (in the case of HS).
Again though, I have to stress...the B&C on this EW is a darn good factory stock. I have Weatherbys and a Sako that came with absolute crap for stocks; at least Winchester is trying.
