A carbon mast will save you about half the weight of the equivalent alu section.
I have never done a boat with anything but wire or Navtec rod so I don't know about the rigging weight. A quick look at a Navtec catalog or web site will give you an answer to comparative rigging weights. Navtec claims its PBO rigging is 80% lighter than s.s. wire.
I don't think the boat would be more "skittish" but it would be stiffer and stiffer is faster.
I had one owner of a 43' ketch who went with a new carbon rig and he said he could not really tell the difference. One opinion.