Hi Werner,
you have to discern between VBar Control and a third party radio.
In VBar Control, you would set collective to +/– 12-14° to check if the geometry allows for the recommended range of values (same as in the PC Setup Software).
Then, in both, you could set the limits for both directions to your liking, this would give a linear curve to both directions.
Now comes the difference:
In VBar Control, you would set the collective curves via the Pro Parameter App.
On a third party radio, you would set the collective curves in the radio (from a handling side, it's the same).
You are right, you only use 50 % in one direction and 100 % in the other direction, for instance, which is usually OK.
If you set up a Scale machine, you could also set up the mechanics so you use 100 % of the servo travel and have e.g. -1° at low collective, hovering collective at center stick and like 9° at full positive if the geometry of the model allows for it, then just mind to Set Zero for the tail.
If you know what you are doing, you can do it
Eddi
Born to fly ...
forced to work.