Don't get your expectations up too high for carbon bars and seatpost making a big difference, given their lack of width and length, respectively. Not saying it won't help, but it's not going to have the same effect as on a bike with wider bars and lower seat tube that gives them more room to "work", though I'm also hoping carbon bars will help mute some of the buzz remaining buzz and vibration from rough pavement(need more rise on my mtb, so am planning to get a 40mm riser and cut down its 720mm Easton EC70 20mm riser for use on the hybrid).
Fork's another story. Having never ridden a bike with a carbon fork before, I was very surprised when comparing my Trek 7.5 FX to the lower end models that I thought I'd be ok with. Wish I'd shopped around to see if there was something with a carbon fork and disc brakes available, but after a couple of back to back rides on bikes with and without the carbon fork, there's was no doubt in my mind that "with" was better. Made a very noticeable difference in the ride quality.