OP, the NightForce is a great scope. Are there other options? Sure but you had better get out your checkbook. USO is a sweet rig, but used prices are ~2k w/ new approaching and even exceeding 3k (model depending of course). S&B is highly regarded as "top tier", at 3k ea.
Suddenly the 1700-2k for the NF doesn't sound that bad
I too would recommend the 5.5x22 w/NP-R1. Although I am running the NP-R2, it's ok but the retical of the -R1 might be better. The ZS is a great tool as is the HS, both have their merits at an increase in $$. Looking back now, ZS before HS...
BROZ- Out of curiousity, why the 56mm objective?