Tried it on Jan. 24th with country style ribs rather than a roast. I put most in a 2 liter corningware, and the rest in a small cast iron skillet. I covered both with foil.
After 3 hours in a 250 F oven, the ribs in the cast iron were “fall apart tender.” The ones in the Corningware were tender, but not “pulled pork” tender.
Note — from now on, do this in cast iron only.