Well, considering the prices I have received for foam, and the fact that I have to import it here, I think I will probably go your way -strip planking, but I have a few problems with that.
First I can't get quality wood here (Romania) or evenly dried wood, second I think wood planking will be heavier.
Corect me if I am wrong:
-spruce has a density of about 400-500 Kg per cubic meter, while suited foam for this will be 80-90 Kg per cubic meter
-total weight of wood core is about 11kg -4mm wood
-while total weight of foam core is about 4kg -6mm foam
-I think wood will soak up more resin then foam, because foam is closed-cell while wood has a natural tendency of soaking up liquids...
So, I think the strip planked hull will be considerably heavier then foam cored hull. But I'm not at all experienced with this, and there are things I might not considered...
I think in the end everything is reduced to the budget size.
Wood cored hull=heavier,stronger,cheaper
Foam cored hull=lighter,less dent resistance,more expensive

And what about wood behavior in long time ?
After all, I'm not such an experienced racer anyway, maybe 10-15kg plus won't make a huge difference unless you are a really serious racer. I think I might end up with wood cored hulls like your build, foam seems quite expensive...