part of the reason I've been looking at the possibility of a planing cat has to do with the ease of building hard chines with marine ply, versus super-narrow round-chine displacement hulls.

Planing on a large cat with lots of waterline has diminishing returns. But at 14 feet, I think it might be reasonable. If the McKees could build a planing cat 20-30 years ago with surfboard blanks and all-aluminum beams/mast, and a crappy sail, I think we ought to be able to do it with carbon and canted boards to add lift.

You're right, it has to do with what you want - I like the idea of two modified (enlarged)Moth or IC hulls with 8' of beam, canted boards, T-rudders and a chute.