Well, logical ops in a render stage in Direct3D 11.1 do in fact require WDDM 1.2 - so they can't work in Windows 7 Platform Update, though unfortunately this is not reflected in the Direct3D documentation.
Ah that makes sense; I should have researched a little harder and not taken the documents at face value. I'm just going to point out again that Direct3D 10 required little research... :smile: Also it's somewhat amusing (or sad...) that even Microsoft has trouble with these feature levels.