I looked at that idea too and looked them up to find they were mighty proud (pricey) of their product. So, I started researching that type of product (not like they worked that thing out from scratch, right?) and got boned up on that whole "synthetic wood" deal with the chemical composition and like. I found that they didn't publish their info so I contacted them to request it. They wanted to know why so I explained I was shopping and comparing - which I was. They pretty well told me to go fly a kite... Really?
So I came to the conclusion that they were just "repackaging" somebody else's product and marking up the price about 250% like it was something special.
I also decided that according to places that actually manufactured such stuff, it was required to be supported at way-closer intervals than what is provided for by trailer support spacing. In short, the stuff is going to start sagging between the supports in short order and that places too much weight on way to little surface.
When I looked at your link, I see where they figured that out because now they've added lateral attached metal reinforcement.
And shipping $ was just crazy.
I stayed with wood. Figured I could replace wood like 30x for the price of that other stuff.