Another thing, I compared these three scopes after sundown until about 35 minutes after sundown to see how they do in low light.
The surprising thing to me was that the Tract lost its resolution quicker than the other two, despite it having Schott glass and costing nearly twice the amount of the others.
The Leupold had the smallest objective while being set at 6x and 36mm obj.
GPO was at 6x42
Tract also at 6x42
So all three had plenty of exit pupil or whatever for viewing low light.
GPO was the clear winner in terms of brightness and ability for my eyes to see detail well past legal shooting hours.
Leupold was a pretty close second, followed by the Tract.
Now if I could just combine the best attributes of each of these into one scope, that would be one fantastic optic.