I had the mark 4-4.5x14x50. Here is my take on the product. Awesome. Some don't like the mil/moa combo but i'm not really going to into that whole discussion. Just learn the gear you run. At the end of the day, just use your ballistic calculator. The first day i had mine, it was set up on a 700 5r and on the top of my truck awaiting a long range session.My friend slammed shut the back hatch, down goes mark 4 and 700 right to the ground and landed directly on the top turret. Did a quick 100 yard zero check and it was spot on and dialed it up for 797 yards as per range finder and it it was bang on. Rugged.
Now for the differences why i bought a NF after.
In my opinion the glass clarity is the same. I have perfect eye sight as per army stats and i give the glass edge to leupold. The contrast favors the warmer color spectrum in the mark 4. The NF has a dim contrast and can lose colors at longer ranges. Example. Yellow balloons on a white backing on a sunny day blend with my NF, with the mark 4 i could make them out on the same magnification.I prefer the warmer color spectrum of the mark 4's. I like the overall features of a NF, etched glass, MOA/MOA which is a nice feature but isn't a big thing for me as i can calculate with mil/moa without a problem. The paralax knob on the NF is much better. If your getting a paralax issue all you have to do is dial to where it is none existent. With the Mark 4, you have to dial all the way to infinity and back to make your paralax adjustments. Basically a full sweep of the knob then find the correction. Can get annoying when barrel heat and mirage start lurking in your scope. Remedy for that is a mirage band and lower the magnification. I switched to the NF NXS cause of the larger objective and the 1/8 increments on the turrets. Overall features of the NF NXS are nicer but i really like the contrast of the glass on the mark 4 much, much better. Without a doubt, i would buy a mark 4 again.
I do believe the overall construction goes to NF just because of the etched glass reticle as opposed to the wire reticle for the mark 4. People slag on leupold a bit saying they aren't this and aren't that. Maybe leupold are a bit behind the times of what the tacticool community needs for the weekend warrior sessions, hahaha, but i am not going to get into that here. I think they are great scopes for the majority of what people use scopes for.... from the safe, to the car, to the range, maybe to the bush and back to the safe... and not the self proclaimed overnight internet forum combat shooting they think they are gonna get into...hahaha.
If your getting a mark 4, I would suggest only buying the TMR reticle...to me, this is the best reticle out there hands down. That's just my take. My next rifle will probably include a mark 4 or a nf nxs. Good enough for my weekend warrior combat....i mean paper punching sessions.hahahaha
If NF is the way you chose, then you have some options. I bought the 8x32-56 np-r1 only because i wanted the 1/8 turrets. Nice for fine tuning but a pain when you tracking fast and at different ranges.Alot a clicking going on. The NP-R1 is best reticle in my opinion for the NF line. I found in the early days of the NF turrets that if you cranked on them fast that they would skip a few. Hasn't happened since but i now turn the turrets at a moderate speed just in case. The mark 4 turrets never ever skipped once. If only NF had the TMR from Leupold....
The other model i would consider is the 5.5x22-56. I did a back to back glass test between these 2 scopes. The clarity is no different at the top end of the magnification. I have to say both models still get the dull blue syndrome around the edges. The dullness comes at the last power on the 5.5x and the dullness starts in between 26-28 power on the 8x model. This test was done in low light conditions. You might ask why would i get the 5.5x model instead of the 8x model. Simple. I like lower magnification. The 5.5 power is nice to have when you play Johnny Lee Swager and try to hit bottles standing in a canoe at 200m. The minimum 8x is a little too much sometimes but manageable. The 32x power is nice to have when the light is low or overcast which is good on the westcoast but yet do i have to use all of it even on a slightly sunny day. You'll get 100 moa with the 5.5x model and 65 moa with the 8x model. All in all, any decision from NF is good. Just decide on one you like. I still wouldn't rule the mark 4 model out though. Take a look through both at your range and base it off that. My suggestion is if your new to scopes like this then get a matching turret to reticle model. My other suggestion is learn the mil/moa so you can be a stud.
On a side note ...i bought the NF NXS from Alberta Tactical Rifle..those are good people to deal with.