Evaporated milk and powdered milk both work in pumpkin pies because they are pre-cooked (or heat treated), the powdered milk won't taste quite a "rich" as evaporated milk but in a rich, pumpkin-custard pie with eggs; it is hard to tell much difference.
This is the same reason that powdered milk works so well in breads and rolls; because the stuff is heat treated already. Most older cookbooks start their bread recipes with "scald the milk, then add sugar/honey and butter to hot mixture" then "allow to cool to lukewarm and add the yeast." Many "modern" recipes omit this step, especially books for bread bakers; there is nothing harmful in using cold and unheated milk in your bread, but I gather that something in the milk breaks down when it is heated to the scalding point and just blends with the dough better. In my experience heated milk breads and/or breads using canned, powdered or butter milk rise better than those made with store bought, unheated milk from the fridge.
I have made really good bread from unheated goat's milk, but it isn't quite the same as cow's milk.
expatriate Californian living in rural Ireland with husband, dogs, horses. garden and many, many cats