In article ,
cavelamb himself wrote:

Jim Logajan wrote:
While searching for videos demonstrating composite construction on Youtube,
I came across this rather dated video of Burt Rutan and Mike Melvill
demonstrating the advantages of composites over aluminum:

http://www.youtube.com/watch?v=7eUt0YnNF3o

Very interesting.
But no information given about the weight differences.

You mean other than stating multiple times that the two parts shown were
exactly the same weight?