Yes, they ARE heavy to flip and rotate, especially the King Size. I struggle doing mine by myself. My set is now 13 years old, but shows no sign of breaking down, I expected it would at this age. My wife and I are going to re-do our Guest Bedroom and put a King size bed in there, and when we do will get a new Royal Pedic All Cotton for us - same as we now have - and move our 13 year old unit in the Guest room.

Yes, you can use a heated pad on it, won't bother it at all.