As far a weight goes I think Coosa is about 25% lighter then the same thickness and size sheet marine plywood. There is a guy on THT that has been soaking a piece of coosa for years now and it has not absorbed any significant amount or water...he posts the results once a year.. here is a interesting thred over there about coosa vs plywood...
https://www.thehulltruth.com/boating...plywood-2.html
strick