A friend and I have a season on some boards made with Polytek 15-6. Tinted and plain off-white. Seems to be holding up. It's a little brittle at first, but once it's fully cured it seems to dent rather than crack. Had no issues with epoxy sticking.http://www.polytek.com/index.php?dispat ... ory_id=249
A few gotchas...
Sets super fast. 5-10 minutes is all you get.
Pour as temps are dropping - evening.
They sell a UV additive. Using it seems wise.
Sand any cross-grain on your core to prevent bubbles.