I made TechPoh's Sourdough Pain de mie recipe this week, and typical of my other attempts at using milk, was way under hydrated. I weigh my ingredients, and I never seem to be able to get sufficient hydration using milk, when using the typical 1-2-3 formnula.
I always have to add more milk or less flour to get the proper hydration.
I also have a milk starter that requires I add about 25% more milk to keep the same apparent hydration as my water fed starter.
I haven't found any direct reference to calculate the additional needed for milk to sufficiently hyrdate.
Does anyone have any insight to similar experience?