The downside to CF to me is that if it fails and you happen to inhale the dust from the fibres, you are going to die, its just a matter of time as the small shards of fibre get in your lungs and poke holes in the cell walls which causes bleeding and infection.
I first heard about this from an ex-military friend who read a report about a heavy equipment guy who ploughed (buried) the corpse of the first Canadian F-18 to crash in Canada. Not long after he got serious lung problems and died. They determined the cause was the CF in his lungs..
Having said that my fav steed, 2000 Devinci Millenial roadbike has a front fork made of CF.
I am saying this to make PPL aware of that danger, not to dis CF.