The only thing I was checking is ranging "repeatability".

Today I was indeed rangefinding and shooting at both 10x and 12x at distances of 2 yard increments from 10 to 18 yards as well as at 50 yards.

For my setup actual ranging repeatability was so similar that I could use either setting with appropriate aiming point "adjustments" and I had a paper target with 1/2" bulls and lines on 1/8" spacing hanging over the metal targets to check the poi. I would aim at a bull using 12x, shoot a couple shots, then change the scope to 10x and take a couple shots noting the poi change, then I would shoot the 3/8" kz using the 10x poi. After doing this I believe that if I were to set up my hft rig FOR the 10x scope power level I think MY ft score would be similar. Today, the main difference I saw between 10x and 12x was that the kz appeared a bit larger at the 12x setting which is indeed beneficial for some ft targets after the kz gets splattered toward the end of the match.

Anywhoo.....you are correct that the close range impact points were different between 10x and 12x when using the same aim point, however the rangefinding at 10x was repeatable enough to consistently knock down my Gamo target with a 3/8" reducer once I had a handle on the different hold point.