I own a PST II 3-15x44 and while I've not compared it to the SHV I have compared several Vortex products to their Nightforce equivalents.
I think that the biggest benefit to buying a Nightforce is their sturdy construction and crisp adjustments, each click of the knobs feels more solid and positive than most Vortex models. As for lenses, there isn't really that much difference between the two brands.
I picked the PST because I like First Focal plane scopes and the zero stop feature. While the adjustments don't seem as solid as a Nightforce they are very good. I also like the lighted reticle, it helps place the reticle better under low light conditions.