You are triggering my memory with this suggestion. I remember our discussions on your Ladder System and the idea of progressively stronger buys as the price dropped to go all in at the bottom of the trading range, and similarly the opposite thing at the top of the trading range(all out).
You'd need to use a log function Conrad i.e. if on one side the price gains 100% (2.0 gain factor) and on the other it loses 50% (0.5 gain (loss) factor) then log(2) = 0.3 and log(0.5)= -0.3
(log(current)-log(bottom))/(log(top)-log(bottom))
Somehow I feel this is very similar . . possibly exactly the same. . .as my idea's years ago to use exponential trading factors relative to the midpoint of the Trading Range (Since logs and exponentials are inverse functions).
I will look into these ingredients and see if I can bake a cake with it:-)