Codeman;
I am currently installing all new composite decking at my camp as we speak and after a lot research I decided to go with a decking called "Latitudes Intrepid". I Installed some of this two years ago at my camp and was impressed with it's durability. I actually used some small pieces of it as shims submerged under my jet ski lifts with no ill effects whatsoever after being underwater all year, not a bit of swelling! Their hidden fastener anchoring is really nice and gives a nice clean appearance when complete, no exposed screws. It's not cheap at $55.80 for a 20' length but when it comes to composite you get what you pay for. The other nice thing about the Latitudes is eventually I will be replacing all my dock boards and they make a heavy duty marine product that matches my standard 5/4" deck board. Here is a link for the Latitudes which can be purchased at Harvey Building Products.
http://www.ufpi.com/product/latitude...g/intrepid.htm
Azek makes a nice deck product as well.
If you want to see the finished product, take a swing by my camp as the deck is 90% done now. Just waiting on glass rails.
Good Luck!
Dan