I've put a lot of thought into both options. Though more work, I believe properly sealed and properly bedded with 5200, the traditional diagonal bottom is just as good as plywood. And it's going to look a hole lot better. You can "score" diagonal lines in the plywood as much as you want, but you will still see the grain going the length of the boat under the paint.
The Woodery in Lunenburg MA, re-saw and planed some 1" x 6" Philippine down to 3/16" for me. It is now sealed with CPES and drying in the early spring sun.
It's somewhat a shame that it's going to be painted sort of "barn house red" bilge color.