Wow, have you actually dried wood to a specific MC and then weighed it? I looked on the wood database and they said sample to sample variation can yield +/- 10% on density.

Assuming both densities are on the low side, the delta between WRC and Redwood only changes by 0.3#/ft3 to 3.3#/ft3. In my case with a Petrel, it's still less than 3# difference for the boat.

BTW, If I'm sounding like some sort of Redwood fanatic, I'm not. I just think the difference between the two is minor and if someone wants to build in Redwood they certainly can without too much additional fuss.