This is a very interesting question.

I know of 2 examples using the same model where this actually did work.

As most bipe pilots, me included, are aware that SIG has the Sundancer. Some of the very first models had issues with the big screw that screwed into the top wing and then attached to the center cabanes that allowed the top wing to part company in flight due to the screw pulling through the wood in the wing. I know of 2 instances where both planes landed without issues, but at higher landing speeds.

If you do a search for the Sundancer here on RCU, there are a few threads on it and the big one has one example in it. That plane was used by SIG to test the updated top wing connection and from what I remember went on to fly very well.

I agree with Rodney, if all things are equal and the wing loading is not to high and the CG is forward, not aft when the top wing is removed then it will fly, but not very well