Excuse me for entering in this discussion without an invitation but I really got confused of what you said.
What air, helium and inflating the wing have got to do with this?
Come on guys, be seriuos!
Light or heavy means what you read on the scale display which converts into wing load. That's it.
Since we are talking about wing weight, I also disagree about repairing foam core wing.
It may be easier but the additional weight it causes is huge, whereas when you repair a build up wing its weight will be the same afterward.
I'd like to point out one more thing. In a built up wing the covering film is part of the structure, it provides stiffness and stength unlike for the foam wing is only an esthetic application.
This has been neglected and I think it would be worth to mention rather than the amount of glue needed when building one or the other, which is a very subjective factor.
One more question. Which building technique do the sailplane guys adopt for their 10 feet wing span-and-above creations? Are they keen on light structures or do they like thier planes diving like P 51's?