Pre-heat the oven to 400ºF.
Place the 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-sides up, back onto the baking sheet.
To the bowl with the potato flesh, add the cheeses, pimentos, garlic, onion, black pepper, hot sauce and mayo.
With a small spoon, scoop the pimento cheese mixture into the little potato skins. Place back in the oven until the cheese is lightly browned, about 10 minutes.