They are different animals - large, heavy, meh illumination, dual exposed turrets (Accupower 1-8) vs small, light, RDS illumination, one or both capped turrets (NX-8).
I had a 1-4 Accupower and was excited about the 1-8 until I saw it.
The NX-8 isn't perfect (few optics are) but it works...