I have three crowntail girls, the two marbles and another more traditional colored girl who's quite slow to grow, and I haven't noticed any difficulty with their rays folding. My little crowntail boy is holding his rays straight, but he's still rather young, I think. Not breeding material tho, a few of his rays are missing the double points that appear on the rest, though once he grows more and recovers from the petstore conditions, he might look better.
I had read somewhere that some good crowns trace back to halfmoon lines. I think it would be a fun experience, both simply for experience and for working to make a better line of CTs.
Maybe at some point if you've got halfmoons available, I can see if they'd suit my goals :D