I can't say I'm a super fast cornerer, but I'm quite happy descending fast.
I don't notice any difference with the carbon bars in terms of handling, they do soak up vibrations and make my wrists happier.
I use the fsa k-wings and like the flat area.
As for carbon wheels... My spinergy rev-x's soak up vibrations and chip seal like nothing on earth... the bike comparatively feels heavy I guess you would say, the wheels are heavier than my others... but I'm fast on themI don't corner hard on them and try to take it somewhat easy 'cause you hear tons of horror stories about those wheels... but they do warp if you corner them hard (the bf has done it on them... pushes the rim into the brake pads).
I don't notice shimming vibrations on descents... I do gain a ton of speed downhill with the wheels. They're a bit freaky on a windy day or if a big truck passes me.