A sandwich construction gives you better specific stiffness for the part it does not help with impact resistance. You want the strongest construction at the areas where you are moving around on the board, only a thicker skin is effective here. http://en.wikipedia.org/wiki/Sandwich-s
Fred you are DEAD WRONG, both in theory and practice,
The sandwhich structure prevents heal denting and impact fracture much better.
if you don't believe me build up some test panels, jump on them. the sandwhich is multiple times stronger in impact with the equivalent number of plies without a sandwhich.
3 plies of 6 oz on 1lb foam will actually fracture when jumped on from a height of about 1 foot.
2 plies of 6 oz + 1/8" dcell H80 + 1 ply 6 oz on 1lb foam will have only a small dent when jumped upon from 2-3 feet.
It is stiffer yes, this stiffness and the compression strength of the structural foam allows it to distribute the load to the lower skin and soft core over a much wider surface area engaging more material and lowering the overall stress and deformation of the structure in impact.
Also to whomever suggested carbon I suggest they run the same tests. Carbon will shatter on almost any impact load when put overtop of a relatively soft structure that will be jumped upon due to it's high stiffness and minimal deformation to failure. (low impact energy to failure) It maybe suitable for the lower skin of a sandwhich where point loads are reduced but I would avoid it's use on the top skin.
Mixing carbon and glass is also not a terribly effective use of materials as the material stiffnesses are so different that the glass is effectively just "along for the ride" until the carbon fails. Really only useful in ballistics applications when you want parts of the structure to shatter and absorb impact energy and other parts to stay intact after initial failure in order to prevent penetration of the structure.
veneer has a similar effect in improving impact , but any of the veneers (oak birch) I've tested have been a little on the heavy side when compared to a sandwhich structure of equivalent impact strength
My vote, if you or a buddy have some thin dcell or core cell laying around (1/8") use this as it will get you the best strength at the lowest weight. . If not veneers should be more readily available, easier, cheaper and better looking .