Hi Baldy, I have a Is 111 (2008) and a CA 58 (and a 52). Personally I found my CAs too one-dimensional: they work only when overpowered, otherwise they suffer; they are also quite nervous in the ride and it is easy to upset the balance of the board especially in choppy confused seas. In comparison the IS-111 is has at least two gears: an almost freeride one at low speed and a very fast top-end (I am not enough sailor to find its top), plus it is very stable. I never tried CA 62 or the new 66, and it might be that some more volume and size helps the boards being more all-around. CAs are small boards and a Is-111 is probably closer to a CA 70.
Construction wise the CAs seem quite fragile, my CA 58 came with a defect on the deck, has two dents in front following some very minor hits from the mast, and the finish is very rough, the Isonic seem to be much more robust and better finished.
You cannot really go wrong with either, but if I had to do again my quiver, it would be built it around Isonics.
If you want to follow a long (and fairly useless) discussion Is vs CA, check out a recent thread on the Maui Sails forum (started with a question on exocet)
Last edited by davide; 18th January 2010 at 01:17 PM.