in my opinion, duna 15 is as good as any other brand 18. maybe even as good as others 20.
as far as cutting, duna is in its own class. next in line is design board. I like it as well. then to me, pb and signfoam are similar.
all brands are better than wood in my opinion.
as far as customer service, I think pb is the easiest to deal with. they have always been nice to speak with, I just wish their product wasn't so sandy. even their 30 lb is gritty to cut. it's a good material, but it is very expensive. in a perfect world, i'd get 20lb 2" duna.