If you're talking about the top wing on a biplane, a flat statement like that isn't taking into consideration:

Where is the center of drag on the airframe as a whole?
Would adding any surface deflection increase the drag on that wing enough to introduce a pitching moment to the airframe?
Changing deflection might actually reduce drag depending on how the original orientation was actually working.
Adding aileron deflection isn't exactly the same as adding incidence to the wing. To get the effectiveness of an incidence change by deflecting flaps/ailerons instead of changing the incidence probably will give the airplane a wing that's throwing a very different L/D at the airframe. You'll probably never be able to get as clean a result as the incidence change gives by deflecting flap/ailerons. And dirty means drag.
And a few more considerations I'm surely forgetting.

BTW, the picture isn't real close, but it really looks like the top left aileron is deflected slightly more than the right. Is that how you flew the model? with the ailerons up? and were they trimmed to keep the model's roll axis horizontal?