I recently finished my first one off, but haven't ridden it yet so can't comment on the longevity etc :-(
Couldn't convince myself that not connecting to the deck would be adequate. I have heard some suggestions that a large area panel would spread the load across the board enough so you don't need to go all the way through, but I think I would wait for others to prove that before risking it.
Some other handy advice courtesy of John at Sanded Aust (thanks John) that I followed:
- use gorilla glue to glue in the HD block (excessive epoxy in this region can melt the EPS)
- I definitely couldn't get it snug in all places after I was happy with the alignment etc. There was several places where the gaps were probably at least 5mm.

I used a layer of basalt cloth and 2 x 4oz top and bottom. The basalt turned out pretty dark and got hot in the sun so I used an opaque tint in the filler - if I had my time again I would use the tint in the lam resin too. I also used 100mm layer of uni directional carbon between the feet, with a double layer over the front of the HD foam insert where the bending moment would be greatest - might be over kill but it was my first one so I wanted to be safe.

Hopefully it goes well, definitely enough time in it to justify paying retail ! But I had fun making it.
Cheers,
Pete.