With my FBL setup, when I fly forward, it rolls left - so it would seem that the blades are reaching their maximum cyclic pitch too soon and therefore the direction of travel is a few degrees off from my stick inputs.
This hurt my brain for a long time... it still does a little bit.
I think I have a similar problem with my HBFP: http://myrcguide.com/index.php?topic=1498.msg46127#msg46127
Two videos follow that post (1st and 3rd post after the link). Do you think that this could explain it?
One other thing I find so cool about helis, is that the main rotor disk is not perfectly horizontal when hovering still. I think it's because of the tail rotor: Besides generating a torque to conserve angular momentum, it also applies a force to the heli as a whole, so the rotor plane tilts a bit to the opposite side to apply an opposite force in order to balance it. Do you think this is a good explanation? Coaxials have no tail rotor and the rotor disks are perfectly horizontal.
I find that really cool! It took me some time to get it, that is, if I got it right, hehe