I lived in Boulder for two years and never really had a problem with the recipes from VCTOTW. The first batch of cupcakes I ever baked after I moved to Colorado sank in the middle, but I realized that was because my baking powder was really old. (Though I did find that adding a few more tablespoons of flour to the cake batter also made for more consist risen, puffy cupcakes.)King Arthur Flour's website
has a really comprehensive guide to baking at high altitudes.