Let me share with you my experiences with carbon fibre parts versus ditto aluminum/alloy parts.
I'm a rower and be racing at the world champs four times now, so I think I know alittle about boats now.
(use road cycling for x-training, by the way!).
During the last 5 years, carbon fibre parts have become more widespread that aluminum/wooden parts in rowing. If you compare two equal top boats with aluminum riggers and carbon tube riggers, they are about equally stiff and costs about the same. So really no diffrence in performance. I've only seen prototype boats, pure carbon fibres that are stiffer than regular racing boats, but they were not light enough to be used for racing.
While parts that suddenly break in rowing are not acceptable, it is in road cycling. We have to use the same boat and oar set for an entire season and cannot risk something that breaks during a race. In road cycling, faliures are more acceptable during races, because you can always get a new wheel etc. Theres always a service car right behind you (if you're good enough
).
This year we got a new type of oars, pure carbon fibre. The oars we had before them had wooden handles. Good wood is extremly stiff aswell, but these new oars were extremely stiff. Really nice oars. As the season progressed, we had some issues with them. Out of 20 oars 3 broke. And I mean broke as breaking into two pieces. I've never seen a new oar with wooden handles do that.
Also at the world cup, I saw a favourite boat from Japan suddenly break a rig during a race. Resulted in the japanese guy had to take a swim. Boat was new - only a couple of months old tops.
What is my point is, if you compare good aluminum parts with its carbon counterparts, they are really equally stiff. Aluminum almost never breaks and it doesn't break just because you accidentally gave it a tiny little knock in the wrong place. Carbon parts cost hell of a lot more than alu parts.
Unless you do races and you're almost pro on a level where you -need- CF parts to take you further, I don't see why you would want carbon parts.
There are good alu parts out there. Good alu frames and alu everything. Go alu!