Ok, F1 cars run carbon chassis so it's possible. Take the following with a grain of salt, I'm not a composite's engineer. No material's magic, carbon fibers (regardless of type) are strong along the axis of the carbon. IE a sheet of carbon won't deform along the edges, and won't bend but most likely they won't take as much load pushing hard into a plate 90* to the fiber's axis. Axial wound could be good stuff, and properly designed might actually make a good cage.
Some of my concerns: Maintenance is going to be far more important. Steel tube cages will show obvious bending and cracking if they're damaged, carbon can suddenly let go with no warning, so inspection is way more important. Design is significantly tougher, metals have some great properties that make them easy to design with. Carbon layup schedules become hypercritical when designing structural stuff, along with that comes expensive software packages. Last for today, with a normal cage you can build to the series' spec and that's good. With CF as structural members, you're going to need a PE with experience to check the design. If you don't have that, I doubt you're getting on track with it outside of track days. If that's the case please don't do it, playing fast and loose with people's safety isn't cool. If you're looking to add some stiffness take a sheet of normal carbon fiber or aramid, come up with a solid mounting scheme and run it from rear strut to rear strut and attach, run down to the floor, then test, it might be a decent amount better.
I understand the concerns with the CF Cage, I don't plan to make an entire cage, more of a roll bar similar to this:
Design Innovations: Carbon Fiber Rollcage Corner Balance
Its in Oakley designs Porsche. Interestingly they found a way to make it create an anti splinter affect, which I believe I know what they used. But some testing and some experimenting at the shop should help me figure it out as well.
Luckily, I have a cousin who just finished up in Mechanical engineering and I have a couple other buddies from when I used to work at an architecture firm that are structural engineers. I haven't talked to them about the project yet but I'll be seeing one next week and I'll ask him about it. I know he has used machines that calculate for load bearing carbon fiber support beams.
I don't plan to use this in my 350z, more just in the 240z behind the seats similar to the one in the link. I'll have to look up any rules and regulations regarding such a roll bar to be used at the track because I don't know of any.
Your right about Axial CF. The weaving machine they use is pretty cool to watch it do the weave around their metal jig.
This may be rumors and a myth, but I have heard of Coast Guard Ships using A pre preg form of CF in the bows of the boat. Supposedly they are able to cut a typical fiberglass/wood boat in half easily without a dent to their ships. I heard this from a guy who used to teach a pre-preg course.