No its not. seriously this is salesman mumbo jumbo, and i sell ski boots for a living.
customs are great, but they arent that much better than a trim to fit if you dont have major issues. the other thing is that a weighted custom bed builds a LOT of arch, if you have a high arch anyways the custom is too much support and will cause instep issues, then you remake it and have less of a heel cup than you would have with the trim to fit in the first place.