Yes, it last through many fish catches. You do have to use a surficant on the fly to dry it after each fish though.
Scotch Guard works on CDC as well because it does not matt the feathers. CDC floats not because of the preen oil, it floats because of all the air that it traps due to its many branched rachiis. Scotch Guard works on CDC precisely because it prevents water displacing the air it retains.