Bob,

The theory on a forward staggered biplane is that the top wing should be slightly positive relative to the lower wing. The idea - at least in theory!!! - is that as angle of attack increases, the top wing will stall first and loose lift. The lower (aft) wing continues to generate lift which is behind the CG and therefore lift the tail/drop the nose, the plane accelerates and continues to fly - - - - in theory. Then there is also theory on how the air is deflected by the top wing, so that by the time it gets to the lower wing the flow is slightly different for the lower wing.

I know I also fussed around with the struts - cabane and interplane - until I found what worked. But the result gave the top wing slightly more incidence than the lower one.

But as with most things in model aviation: Use what works for you. And if it works, don't mess with it!

tree2tree