The only carbon tubes systems I have seen are the ones that use EVA foam to mate the front and rear. A graphite arbor like you are using would definitely work better.

These grips are made from a rigid, dense material that you can shape like cork. Once the grip is shaped graphite is wrapped around it and epoxy bonds it to the grip. On average they weight about 10% less than high quality cork but I am all about light weight so I have been pushing the limit. I can get them lighter but then you are messing with the balance of the rod. All of the new North Fork Composites HM blanks are so light that you can use a split carbon fiber grip and get the balance point about an inch in front of the reel seat which is pretty amazing. My 10'0" NFC HM blank has a split carbon grip and balances an inch and a half in front of the reel seat and that is with my stradic ci4 reel. With a regular spinning reel the balance point is an inch or less.



I use a full grip on some rods that are going to be in the rod holder a lot.