How's the glass between the two, also how do they compare for the eye box and paralax? They both track and hold zero dead nuts on?
I'm not a glass junky, so take it as you will. Both sport ED glass, and IMO there is absolutely no reason either will hold you back optically. Many have stated to notice "fisheye" distortion around the edges of the FOV at max power in the NX8s, moreso in the 2.5-20, but if it's there I certainly don't notice it when I'm shooting. I have no problems with the NX8 glass on either model, and I consider the image quality very good to excellent. Not quite ATACR excellent, but you may not notice the difference unless you're comparing them side by side.
The March handles glare better than any other scope I've looked through. My only gripe with the March is that image quality degrades as you exceed 20x in the 2.5-25x52. It's still awesome, it just not as awesome above 20x.
For parallax, I prefer a fine adjustment and I really like the short travel of the March. I like it when I adjust to the point that the image is as clear as possible there is no parallax present. This is reality with the March. The NX8 takes a little more fiddling, but it's a vast improvement over the NXS.
I don't have any problem getting behind either the March or the NX8s. As I stated in an earlier post, setting proper eye relief is critical with the NX8 to minimize eye box issues, likewise for the March.
Turret function in the NX8 is classic NXS style along with the Zero Stop. The performance is everything you expect from NF. The March is excellent as well. Mine has never failed to track perfectly and it returns to and holds zero 100%.