After reading this thread I checked with airush on the Monaro, more out of curiosity..
"we are using a full 160gm Carbon top and Bottom and a full Corecell Sandwich top and bottom. This is the most expensive way to build them and I cant see a lighter layup holding up!"
I have seen it time and time again in the windsurf industry (I raced at international level for nearly 15 years) and if you are prepared stick your board back together on a weekly basis and put it in the bin at the end of the year then you can get the weight low, but for production...?