How many miles should I expect to get from a good trail shoe. I have found a pair that are a great fit and need to know how many to stockpile for a thru attempt. They are Garmont Momentum without gtx and I'd like to buy enough for a thru before they change models or go off sale. They seem pretty sturdy with a vibram sole and I'm guessing I need 3 pair. Should I get 3 or 4? Thanks.