it is nice to see that you are happy with out products.
You have answered your questions.
For middel tone colors like grey, blue, red, yellow, etc. we recommend to use the Micro Mask.
We are still working on a medium color mask, but is is not that easy unfortunately.
If you use the dark mask, you can decrease the Shadow Tolerance to 0. That will make sure that only pure black will be deleted. Maybe this helps. If you use the light mask, use 400 for the Shadow Tolerance. Check the result in the preview before printing.