Preheat oven to 400ºF.
Place potatoes on a baking sheet and roast until tender, about 40-45 minutes. Remove and set aside until cool enough to touch. Cut each potato in half and scoop the insides out into a medium-size mixing bowl. Place the skins cut-side up back onto the baking sheet.
To the bowl with the potato flesh, add cheeses, pimientos, garlic, onion, black pepper, hot sauce and mayo.