One time I bought some grey mini-cell foam from a foam supplier and it wasn't the exact kind that kayak shops and suppliers sell. It was a bit more rubbery / flexible. It didn't carve as easily. The kind that the kayak stores carries has a numerical designation like 102 but that's just an example and not the number. If you could send them a sample it would be good because you may end up with something like I got. There's hundreds of variations of mini-cell. That just means it doesn't absorb water. As far as the micro-cell you refer to, I don't know. Your site says used for kayak seats but doesn't say for carving. You might do just as good price-wise at CLC.com. and there you know you're getting the right stuff. Many kayak stores carry it and without the shipping but with tax it might be the same price as your source.

I wish someone on this BB could find the secret source where the kayak stores get it from and the exact numerical designation.