The only glassed wing I have is from a Sig Kougar. I can see it adding strength. One of the problems however is if you do the top part of the wing and then the bottom, and the plane is a top mounted wing like on an Ultra Stick, and you trim the covering to do the job, how are you gonna re-cover the part that will show in that the re-cover job looks good without any humps from the cured fiberglas? You can sand but once you get to a point, you've sanded away all the strength that you wanted in the first place.
When I join wing halves together, I epoxy all the spars and the whole length of the root. Only had one wing come apart on a Cessna Skylane but it was due from a crash.

Dave...