Tell us how ur future 50' Wong shoot like.
On the subject of carbon fiber, I want to explain in the best of my limited knowledge.
Carbon fiber is one the stiffest material, pound for poud stonger than steel. It is an aerospace and high performance boat buliding material. Aerospace probably first, they are always ahead anyway. Carbon and Kevlar is within the same gang, aramid fibers, exotic stuff.
Spearguns builder using this stuff lacks the long term testing of users like power boat builders. Power boats especially racing ones realy torture carbon fibers to the limits. If you see the prestigious American cup, one of the main sail mast made of carbon fiber can cost US$1 million each for the racing yachts.
Beings stiffest and strongest weight for weight might not be the best in long term usage. Carbon fiber is like the structural material and they have to use resin (glue ) to bond them together. If a builder has good budget, epoxy will be the resin. Vinylester and polyester are the other choices , less exotic but cheaper. 50/50 ratio is about right. Good bonding technique will be by vacuum bonding. Less resin is best.
The main concern of getting nick on carbon fiber barrel is not only nick as in damage, the worry will be water absorbtion cause the exposed strand of fiber which will pick up water/moisture like a candle wick sucking oil. Delamination will occur and thus strength will be compromised. Titanium does not suck water as with all metals.
If a barrel is using epoxy resin, UV from sunlight will kill it fast. Other resin can survive UV better, but less strength. A compromise. Kevlar is another "no UV ray please" material.
If a Wong Hybrid at 50" is design to take 2 x 9/16 bands and if it can accept 2 x 5/8 bands, Titaniun or carbon fiber barrel is already more than adequate. Even a good aluminum barrel can survive this lousy power of the bands. Manufacturer loves to put exotic material where it can boost sale cause it sound exotic.
Other weakness of carbon fiber is that the strength of the barrel will depend on the orientation of how they lay the carbon cloth. In boat we zig zag 45/45 and so on, so that we get strength from all side for wave impact. It will be natural that the carbon fiber barrel will be oriented in respect to the band pressure but the screw attachment for ur shooting line and installation will be the weak link cause the carbon fiber orientation does not focus on that part. In boat buliding where we need to mount something that has great ripping power like big bolts for some big gear, we use a backplate to distribute the load. This u won't find on speargun barrel.
If you want long term service life I am sure Titanium will give you more. But again speargun is consumeable item, we learn of their reliability from using and abusing them.
If Mr. Bettua said that carbon fiber does not nick, this is marketting my friend. Unless u are talking of Zircon Oxide or diamond against a reef or wreck, other materials will at least nick.