The Barring in a Barred Rock is supposed to be more black and white, and on a Dominique they are supposed to be not quite black on not quite white in a slightly different kind of pattern. I forget now its technical term, but it is less orderly striping, more camouflaged looking.
It's called cuckoo barring. I like your description of the main differences, nicely put.
And I've heard of a LOT of people recently ordering Dominiques from large hatcheries and getting barred rocks. A straight comb will sometimes pop up in any Dominique line, but with nowhere near the frequency folks are reporting lately. More likely is the they are winding up with barred rocks, yes.