I like the roto-boats for the price. Also; I think it is hard to be competitive in that market with such a bottom line. There are issues with the material being degraded by chemical agents and UV exposure. Yeah; if it gets warped than it has lost much of its structural integrity.
Kevlar works great; but, there are much more cost efficient woven products for drift boats. I think it is a little overkill; but, well worth using if you do not mind spending the extra money in building your own boat. After repairing a few name brand drift boats; I was extremely surprised to find some odd use of directional mat in certain areas of the boats. Maybe they were just short on their specialty types of mat the days they were laying these boats up.
Fortunately; I was able to work under some of the top glass men in the World back in the day.