tomPietrowskiIf you have finished growin there is need a reason not to go custom. Trim to fits never support the full medial arch at best they offer some mid tarsal support but will still aloe most feet to travel to there maximum pronation. This is not good in a boot. Not only will you potentially have to upsize due to the foot expanding but more importantly you are not in a strong position bio mechanically.
In the 5 years of working at a shop we always at the least got the people into superfeet trim to fits, if not a full custom footbed. They are pretty good about offering 6 or so different shapes with different levels of support. I cant recall many instances of a trim to fit making someone pronate more in the boots and making them upsize. Maybe 3 times over the years they had legit flat feet and the trim to fit did nothing. My experience and .02 cents.
Not wanting to argue, and customs are the way to go, but superfeet TTFs are better than the stock shitbeds.