FWIW, my son's bike has a carbon can on it, and we can put our hands directly on it after he's ridden home from work, so I'm assuming that the carbon cans dissipate heat more efficiently and so don't need a heat shield to protect the pillion's leg (or Your panniers I guess)!
I'm thinking of going for the Delkevic carbon can on my Glee, but I'm stingy so I'm letting the original get a bit more tatty before I replace it