Do you know if the calipers are painted or anodized? I've never seen them but I've read that some high end calipers are anodized. If that were the case they may require extra attention, if they are painted, I would assume any quaity wheel cleaner would be fine on the calipers as well, treat them like you would a painted wheel. If there is a lot of baked on brake dust a product like IronX just might be the ticket. As you know, it's a good idea to make sure wheels/brakes are cool when cleaning.