Dave Pascoe Marine Survey had another good article:

http://www.yachtsurvey.com/core_materials.htm

It doesn't look good for synthetic cores. I think wood cores are at an advantage since they have higher shear strength, and are a bit less likely to delaminate from the facing.

You can definitely see the disadvantages from doing a cored boat in a mold--where we build all one-offs, we're more assured of a good bond between our glass face and the wood core.

One can draw some good analogies between the balsa cores discussed in the boatbuilding.com article and our cedar/redwood/spruce cores. While a stripper's woodgrain isn't running perpendicular to the faces, wood strips still have decent shear and compressive strength.