I bought a 5.5-22 about a week ago, and I am absolutely crazy about this scope. I would think that it would be plenty of magnification out to 1500 yds. or better. This is only my opinion because I had not had the chance to shot it past 300 yds. yet. I have looked at several objects beyond a mile away, and could get a good sight picture on them. I do not think that you could go wrong with either of them.
i don't remember having any problems lining up on a groundhog at 1030 yds with my Lupy set on 16X. the more i shoot long range the more i favor a little less power setting. when i first started, 20 seemed like it wasn't enough. now i shoot on 12 and 16 power for most of my shots. it's a personal prefference thing but a 5-22 scope is hard to beat for the distances you mentioned.
As an additional benefit the 5.5-22 has more elevation and windage adjustment than the higher magnifications. I to find the even shooting 2000 yards 22x is plenty. In about 1/2 the conditions I shoot in 22x can be a bit much. You'll love the NXS it is "the" scope.
cheers 
Linear Mode
