I've never really seen the point of carbon bars to be honest, they don't even seem lighter than a good alloy one. I wouldn't have thought that they'd have any more affect on ride quality than padded bar tape either.
I've never had any carbon bars but I think their main selling point is comfort rather than weight.
I recently swapped an alloy seatpost for carbon on my mtb and it made a huge difference to the way it soaks up vibration.