I assume you're talking about PowerCordz and suchlike. They're an unimportant amount lighter. They are more difficult to clamp. They are more sensitive to chafing. The ones I used actually were a bit stiffer, but it's a feel thing rather than a function thing.
I like Dura Ace 9000 cables, they do make the componentry feel smoother, these cables made my 105 brake levers feel like Ultegra and a friend of mine swore he was using Dura Ace levers when he rode my bike, not sure if I would go that far but I will go as far to say that they feel a lot like Ultegra.
The same people who go for ceramic bearings I suppose.
To me, they were basically same, same, but different.
Once in place they did the job just as well, while being a tiny bit lighter.
Harder to clamp, but easier to cut.
More sensitive to chafing, but doesn't fray at the end.
Pick your poison.
If I didn't have better and less expensive things to do, I would have liked to equip a bike with Nokon-style outers and PowerCordz cables. That combo would have had a theoretical advantage in stiffness - less compression/extension, which might have done nice things to the performance of the braking and shifting.
Powercordz cost about $60 and save 60 grams. They supposedly last forever and resulting ins smoother, more direct breaking feeling. I have two sets laying around but am too busy riding to put them. Two of my frames have convoluted internal cable routing and threading standard cable is a pain because of inevitable fraying.
There are people that actually believe the gunman was on the grassy knoll, the moon landing was filmed in a studio sound stage in California and Simple Green dissolves a bicycle chain. There was one lunatic that actually believed you could ride a Campagnolo UltraTorque Hirth joint crankset with a 1 MM 'air gap' separating the crank spindle halves.