Been doing some looking. Is the leupold MR/T 2.5-8x36 a FFP?
I don't think Leupold makes an FFP optic other than the 6.5-20x50 LRT M1 (there might be an 8.5-25 FFP as well).
I'm not a big fan of using low-power optics at 600yds unless you've got a good spotting scope (and a good spotter ). Understanding also that you don't want a beast of a scope weighing down that AR (what caliber is it btw?), I'd go the NightForce route if it were me.
The NP-R1 reticle is pretty awesome and I've looked more and more into going the MOA/MOA route - I don't feel like the extra hash-marks are unusable for long-range over the NP-R2, so you might consider that.
What's the primary purpose of this rifle? I don't know why you would need to range quickly unless you're planning on hunting with it - and if that's the case, then a bigger scope might come in handy with more magnification and yet not so much loss in FOV.
Check out Vortex Optics - they're a cheaper brand-name, but LowLight over at Sniper's Hide did a review on the Razor HD model and its pretty impressive:
http://www.youtube.com/watch?v=7pc-aov6G7g
Either way - you need to post up some details on that rig man - its sharp looking.