MultiWii

One question: Are there any thoughts or proposals to make the throttle independent from batteries output-voltage / current payload, etc? My requirement is to ensure, that hovering is exactly at 1500 Throttle RC, which is NOT altitude hold, but a kind of calibration of throttle..Ty for any ideas, comments...

What you are describing IS altitude hold. The copter has no way of knowing if it is rising or sinking without a baro.

Maybe I was not clear enough. In my opinion, is NOT alt-hold, as I want to adjust the throttle scale according to the propulsion systems capabilities. In that
case external influences, as e.g. wind should not be covered.