So it sounds like it was at least 80% NS-driven, so might as well be considered a Miller B.
That was probably the most intense snowstorm I've ever seen IMBY, with the way it just blew up at the perfect moment to clobber all of northern MD. Made even the other historic storms look very gentle, so I can see why a setup like that so rarely works out for us, whereas coastal New England is probably much more familiar with that type of system.
I do remember many posters being nervous and skeptical of whether it would even work out, in spite of the perfect H5 vort passes that were modeled (probably due to the insane NAO), just because that type of Miller B screws us over nearly every other time.