Loupus, I am not the expert in theoretical aerodynamics, but I can tell you that most models I've flown will roll more axially with some amount of differential. I have got to the point where I routinely set up my aileron linkages with some built-in differential (both aileron servo arms rolled forward 5-10˚ from perpendicular with ailerons set at neutral). What theory tells us is that lift induces more drag, so that the lifting wing with the aileron going down will pull the plane off axis in a roll. What you will see is, as you roll the fuselage does not stay on the flight axis, but wanders a bit as it goes around. When I set up a new model, I look for some visible difference between the two ailerons at full deflection, the up-going aileron somewhat more displaced than the down-going. Then I fly it and see if I think it needs adjustment.

This never concerned me at all until I started flying pattern, in which rolls that are anything other than axial will be downgraded. Now that I know about it, it bothers me when I see any of my planes rolling with a wobble. Before I knew about it, I would just throw the aileron stick over, the plane would roll, and nobody ever said to me, "Hey, you wobbled."

So if you have 10 mm up and 5 down, that could be OK, although it sounds to me like a bit much of a difference--but maybe not. Best way to know is fly the plane. My Futaba TX provides for adjusting differential by pushing buttons, and I don't know exactly how JR's approach may differ. If you're off, it's not going to be a crashing problem, so don't lose any sleep over it.

I will say, once you're sensitized to the axial roll business, it is a lot better when your rolls look like you're on a rail.