OK, I have put some thought into this, and theres one major flaw with thinking the bike 'falls' into the corner without the influence of gyros, and its the one force that cannot be cancelled out while on earth.....gravity.
Watch a GP or Superbike race sometime, and pay close attention to a particulary tight corner.....see how fast those guys slam the bikes over? Gravity alone cannot do this....if you need proof go hold your bike upright, then tip it just off center and let go....it will fall but it takes a second or so for any speed to build up. (You dont really have to do this, just using an example). If gravity isnt moving the bike over that fast, what is?
secondly, a spinning wheel is a gyro, and it will have a gyro effect whether you want it to or not. The laws of physics state this, and your front wheel is a gyro, you cannot deny any of this. I honestly wish I had the Cameron article handy (the web is horribly understocked with his material), as he explains it in ways anybody can understand.
And Mille, youre right about the balancer mass being constant, but so is the crank mass, and they spin at 1:1....your theory here is flawed, sorry.
And if Aprilia wont tell anyone their balancer formulas, maybe they know something they dont want you to know.
at any rate, any decent mech engineer (banda?) should be able to figure it out. Its just math, albiet very complicated math.