The carbon fiber rubs off. I'm with Doc, fake carbon fiber is fake cool. Go with the black one.
That said, I've gotten rid of all mine. My hands don't work so good and they're awkward for me. I pinch the web of my thumb with them and bleed on stuff. I have gobs of Xikars, they work great and I have yet to make myself bleed with it.
Either are great stuff, it just boils down to what you like.
I like this Xi3, it's my favorite ever and I even had the Mammoth Bone cutter...
