Jim's right about the good way to get a smooth finish. If you look at my how-to video, viewtopic.php?f=107&t=2365117
in the third one at about 4:40 you'll see me smoothing a vinyl top half-bag onto the board. If you have a choice in what vinyl to use, I think it is better to go with slightly thinner stuff. The thicker stuff will hold creases slightly, since it is stiffer.
I bet that if you were to do a real dry layup and then fill the weave with a hot coat of resin, you might get a board weighing 50 grams less if you are lucky. Or, it might end up almost the same.