[billybek]

Getting the right shell is probably the most important thing about boot fitting. I have very difficult feet to fit into ski boots.
If the shell is too big you will be constantly cranking buckles and making tight or hot spots. That can also cut down circulation and cold feet on cold days is the result.
I am probably due for a pair of boots. I think mine are packing out and I am running them too tight as a result.
One of the bootfitters I have talked to utilizes a shell that fits in length but it a tight fit everywhere else. Through stretching (punching) and even grinding shell material the shell is custom fit to your foot.
Go to a good shop and they will know how to set you up and at the end of the day you need to be comfortable so be prepared to spend a few hours at the fitter and plan on returning a few times to have the boots tweaked from time to time.
This is why it is usually better to deal with a local shop, for the return visits.