My Vario is calibrated according to the factory directions: begin to hear motor loading at finest setting on the macro slider and midway on the micro slider.

The "Vario Second Look" thread mentions a Kyle Anderson tweak for best espresso performance. It's not referenced anywhere else on the forum that I can find. Are people finding the tweak gives better results in the cup?

You just want the micro setting near the middle for standard espresso. If it's near an edge, you may need an extra click and have to use the macro slider = not optimal.

Baratza's troubleshooting section has instructions and video for common adjustments.

The Second Look was posted long before these instructions/videos existed, so you may find similar instructions posted by Kyle et al in the forums but they're superseded by the instructions above.

I set mine up using a 3 oz shot glass and a digital stop watch

I measure 18 grams of ground beans and adjust the grind setting until I can pull a 2.25 oz shot between 18 and 20 seconds. Once I get dialed into that point I don't touch the grinder again until I get different beans/roast then I have to do it all over again.

each group of beans/roast requires that I "tweak" the setting to get back to my preferred pull window.

I never worry what setting the grinder is at as long as I get the end result I am after.

Right now My Vario-W is set at 3-J (for an 18.45 second 2.25 oz pull). Who knows what I will need to change it to when I get different beans in it.