Jeff,
The blue stuff is a bit better than the pink stuff (tougher, more dense), but neither are very resilient over time. What we are finding is that after some time, while the foam that is actually glued to the wood stays, the foam that is behind it is letting loose, and the ply (along with a very thin layer of foam) starts to blister and will eventually delaminate. My suggestion is Divinicell (what used to be called Kledgecell). I comes in a variety of densities (the 4# works very well) and glues VERY well to wood. It shapes nice (machined, sanded, whatever), and doesn't warp over time. It also won't rot if you happen to breach your wood skin and get water in it. Here's the best part: If you go to www.diabgroup.com and get the number for the nearest distributor, you can usually get a free sample that will last the average boat builder several years (34"x48"x whaterver thickness you need).
Thanks. Brad.
Titan Racing Components
BlackJack Hydros