I installed my keel, at the beginning of October, and have sailed every weekend since. I did not install washers only because, when i lost my original keel, I also lost one of the brackets, and had a new pair manufactured. When I installed it there didnt seem to be any play side to side. I only plan on pulling her out every other year, but I may pull her out next summer, to install a knot meter/sounder. (I know that summer may seem odd to pull out a boat, but the winds are really light in the summer on the west coast of FL)
As to the keel, I really dont know what the new one is made out of... It felt like plaster of paris.

It didnt feel like just plain epoxy, but I am not really a materials expert. I can tell you the old one had some coating over fiberglass, and a really dense foam for the core. Sorry I cant help more than that. I do have some pics of my old keel, it may show what the inside is made of.
You know I just blindly took what Foss gave me and installed it. It makes my boat go straight. That was good enough for me.

But Bob at Foss was really nice, and I am sure that when you call him, he will tell you anything you want to know. He even said that I could come to the factory and see how they make them. Its only a couple hours up I-75 from here.