CAS are pretty much just as good as naval bombers early on, but their naval attack and targeting does not increase with tech. Nav3 will do 2.5 times the damage of CAS3 to ships and have higher naval targeting to boot, so if you're relying heavily on carriers you will eventually want to research and switch over to naval bombers. Fortunately, this isn't too hard (other than the annoying micro off adjusting every carrier) because you can still use your obsolete carrier CAS from airfields to support ground troops.
Obviously, if you want to use carrier CAS to perform regular ground support missions it might be worth bringing them along regardless, and if you're really struggling for research and are using carriers as more of a secondary thing it might be better to just stick with CAS, but if you're going full base strike naval bombers will eventually eclipse CAS in that role.