[material science nerding]It's pretty well documented in a number of other building threads that it can be an issue. I suspect when comparing CF to a very dense/heavy wood it would be comparable. For lighter woods it appears to be a weight savings when they're omitted. I'm no expert. I own a Status neck which is a very thin layup and is hollow. Despite being hollow it weights almost the same as a similar Warmoth maple neck that I own. Given that single comparison the wood is considerably lighter by volume than the CF since one is solid, the other is hollow and they both weight the same.
Perhaps to be a bit pedantic, but, there is a huuuuuge variety of what "graphite" / "carbon fiber" is. There is a huge amount of material difference in them, which influence their mass and density wildly. I would be kind of surprised if the same CF is used in reinforcement rods as is used in say a Status neck, but, I'm not TOO up to date on the exact materials either uses (and I'm not sure it's publicly available information).
[/material science nerding]

so not sure about Dingwall being much interested in making me an artist! I believe it was just a random suggestion to a random customer.