I don't think speed of movement is that big of a deal. Its all about dynamics because most of the snow usually falls in a 6-12 hr window, anyway. How impactful if is that extra 6-12 hours of shreded returns?
This is why we continue to get huge events amidst the compressed background flow. Now, if you want to argue that the fast flow will make phasing more difficult, maybe, but I don't think we are there yet.