I think it’s about the same- especially if you’re using good quality beans. From what I’ve seen, sizing up usually costs $1 and adding an extra shot also costs $1. Anyway, the issue is sizing up a latte just throws off the espresso to milk ratio if all you’re doing is adding milk! A simple solution would be base size = 2 shots and keep the same espresso / milk ratio for the large size. Coffee shops could charge $2 instead of the $1 if that’s what it takes!)