Can't help you past 400 yards, but I have a 3-9 Mark AR that has performed up to expectations. It is basically a VXII with the turret added. It is a sturdy scope with good optics, especially considering the price.
I found I could get better precision at all ranges by sighting in at 300 yards and locking the dial at "3" than by sighting at 100 and locking it at "1". It was off a couple inches at 300 when sighted at 100. When sighted precisely at 300, the poi at 100, 200 and 400 is right on with 55 gr. bullets.
I have no experience with Nikons but am happy with the Mark AR so far for my recreational and hunting use.
