Sam

That's a commonly held belief, but not true at all. In reality, CF yarns generally absorb less because of the yarn layup and nature of the fiber. Amoco, a supplier of carbon fiber yarns, refers to their yarns as "tape." CF yarns lie flat, have less interyarn void space size versus fiberglass of comparable size. In addition, the yans wet-out and squeeze out excess epoxy generally easier then a "round" yarn" due to their shape. What people experience with using CF is the fabric drawing in epoxy readily, seemingly absorbing epoxy. It's a common and obvious conclusion based on using the stuff. It's when you compare the amount of epoxy used to the layup is when you see the difference. Still, in a sense one can say that CF is a sponge in the way it draws epoxy in versus the wet-out of fiberglass. Kevlar aramide is the "exotic" that sucks up epoxy like a sponge and swells to a degree as the yarns absorb the epoxy, and its a bitch to wet-out kevlar and draw excess epoxy out.
Another common CF belief is that it's hard to work with. CF sands fairly well but requires a little bit more work then fiberglass.

To get an idea of the uses:
I built a series of forms to make internal door impact shields, using multiple layers of CF, bagged it down, using 4 oz of Raka per panel. That was too much epoxy and I had to trim it down to 3.5 oz. I then took those panels and cast in s/s inserts to allow a bolt to be afixed that supports the window deflect shield (on the car). Did the same for the 4Runner, too with that insert, but s/s grommets to line the mounting holes. Both car and truck have large CF panels cast for the roofs to lie between the inside steel skin seperated by a thin layer of neoprene sheet, in which the roof liner is then attached. Thiese fabrications saved a lot of weight over the steel, or lack of any steel. And were relatively easy to work.
Of course I wouldn't do this if I hadn't had a roll given to me, but the point is that the rigidity and strength without weight were goals I looked for. Only the CF provided that. Even fiberglass would have been quite a bit heavier. Kevlar would have been a nightmare.

Downside to CF is that it's rigid right up to the point that it breaks, though quite stronger then an equal weight of fiberglass. There's no warning of too-much but a loud crack. Multiple layups of thickness on the other hand delaminate fairly predictably, absorbing quite a bit of energy which was a desired effect for the door and roof liners.

I highly beleive in CF for many applications, and wish it came in clear, too. The price though is incredibly high, so in many people's minds the cost-benefit isn't there in most cases. A friend and I are building his yak with a target weight of under 35 pounds yet have the strength in it. Only CF would allow that. The cloth we chose for that cost Dave $244 USD with my discount. Still, we're looking for that weight savings.

: In addition to 5.5 oz of CF weighing nearly the same as 6 oz of glass, if you
: achieve the same resin volume fraction with both the CF and the glass, the
: CF lay-up will weigh significantly more than the glass lay-up.

: Sam