I don't think that the ribs being honeycomb makes them any stronger (or lighter). Since the ribs are basically only loaded in shear, having a thicker rib structure doesn't benefit you much. The honeycomb stuff in the middle is thus not adding anything really.
As far as I understand, the wing skins are bonded to the ribs, as they are also on the Grumman AA-series, I think. I don't know how the results compare pound-for-pound compared to a conventional RV-type construction, but I guess you do get to play with glue!
