I’m pretty sure Ryan has cut carbon fiber sheets for a quadcopter. I’m surprised there isn’t a gallery for it.
I am going to guess that the trick will be a small build (in X, y, and especially z) and going slow enough to cut through in one pass. The sheets are always very thin, right? Doing it in more than one pass would mean you’ll need a very accurate z throughout the entire area (if you’re trying to take 0.5mm depth of cut, and your of by 1mm, you might be taking 1.5mm instead). That will be the only difficult part. So just plan on cutting through in one pass.
I would also highly recommend going with a couple of good bits. It’s my understanding it will dull them fast and if you don’t start with a hard or sharp enough bit, then you might as well be using sand paper. And watch out for the dust.
As for the maker pipes, I don’t see any way that will make a corner close to the size you need. Changing the x/y planes will make the center gantry bind up, rotate, and won’t make the z more rigid, just more wild. When you build your machine, I think you’ll appreciate what I’m talking about. The normal corners are more than adequate. They are only trouble when you’re trying to make a 3D printer (so 12" high) and cut wood with it. If you build your with a 1.5" Z, you’ll be fine.
Also remember that increasing the size is just buying new conduit and longer wires. So start small.
Hopefully Ryan or anyone else that’s cut CF will come in with actual experience.