Would the NH roo X Barred Rock also be sex linked? I read that non-barred/barred would produce sex linked chicks as well, but I'm not sure about the use of the NH for that.
Yes, the offspring will be Black Sex Links. Any red gene roo (RIR, NHR, or Prod. Red) X any barred hen (BR, Dominique, or CM) will produce Black Sex Link offspring (male chicks are black with a white spot on top of their heads and females are solid black). The most commonly used BSL cross by hatcheries is RIR X BR, but your NHR will work just as well, and like the Red Sex Links, the Black Sex Links are egg laying machines (better again than either parent breed). If fact, my Black Sex Links have been friendlier than my Red Sex Links and have laid slightly better in really cold winter weather.