Lighter, stronger, and can (depending on the material and design) absorb some vibrations.
Ti is nice for the strength. Carbon rails I'm personally sceptical of, thinking it more like carbon bars... very little weight advantage and the varied stresses don't necessarily mean it will actually be stronger. I prefer my bars and saddle rails to be metal. I'm sure in time this will change though... when people stop just making traditional metal shaped things out of carbon (which would be best suited to a spider-web type mesh design I think).
Lighter, stronger, and can (depending on the material and design) absorb some vibrations.
Ti is nice for the strength. Carbon rails I'm personally sceptical of, thinking it more like carbon bars... very little weight advantage and the varied stresses don't necessarily mean it will actually be stronger. I prefer my bars and saddle rails to be metal. I'm sure in time this will change though... when people stop just making traditional metal shaped things out of carbon (which would be best suited to a spider-web type mesh design I think).