Excellent, this is gold information, thanks.
So I guess I will try to keep delta=256 for my yoke and rudder (Saitek), but will experiment lower delta for trim wheel (Saitek). For example, while I cannot have FSX running while I adjust FSUIPC (hence the post), I can still run Saitek Control Panel, where I have a graphical view of signal transmitted by wheel (a red bar that goes up and down). I noticed already that one step of the red bar (it does not move smoothly) correspond to about delta=100 in FSUIPC, but that varies a bit... Obviously I would like trim control to be smooth in the aircraft, and that is why I also use a "slope" that is flatter in the middle (where I want it to be less sensitive and more precise) and steeper at ends. I am wondering if a smaller delta would make sense, here...
I guess the same reasoning would apply for lever to control throttle, prop and mixture (Saitek). I will experiment with smaller delta for those as well, just to make the control as smooth as possible (especially important for throttle, I find).
But I understand the overall sense of your answer, and I am not tempted anymore to go crazy with small delta! It is also good to know that the range is always made of 32768 values, so that I can pick a delta that gives a discrete number of steps:
Delta = 256 --> steps = 128
Delta =128 --> steps = 256
Delta = 64 --> steps = 512
Many thanks for your help. Top customer service!
Cheers