Re: Nikon Monarch X 4-16x50
I don't know you are comparing a Nikon Monarch X to a PST in terms of pricing. Optically, the PST is superior, but the issue is price. The Monarch X used to be sub-$1k, but they're all now in the $1200-1300 range. That's Leupold Tactical territory.
You're talking about the PST, which is $699 for SFP and $849 for FFP, and it has matched reticle and turrets.
The Nikon is MOA turrets and a SFP mildot reticle. You might as well get a Leupold LR/T and get a scope with a better record for that price. For not much more than that, you can just get a NightForce.
The better question to ask would be Wait for the PST, or buy a Bushnell Elite 3-12x44 or 4-16x50/Weaver Tactical 3-15x50? Or just go to the Optics for Sale forum on here and pick up a used Leupold LR/T for cheap.