Hey man, looks like you narrowed it down. They are both good optics, but I would pick the Burris for a couple reasons.
1) I believe the SHV only comes in 4-14 but I could be mistaken. The added power will help with that beast of a rifle.
2) FFP - First focal plane means the increments on the crosshair stay the same no matter what magnification you have it on. Better for just about every situation.
2) Uncaped turrets - quicker and allows timely adjustments. I have found I am putting uncapped turrets on all my hunting rifles. Esp with the zero stop the XTRII has, its a non issue
4) Illumination - does the NF have it? not a huge deal unless hunting.
5) mils - all the cool kids are doing it. Meaning, if your son finds some shooting buddies, its best to be on the same page for calling misses/hits etc. If his buddies all use MOA, then I would say to do that.
6) 34mm tube - added strength, even though I don't think that will be an issue with NF. They are bullet proof.
7) they are the same length and the XTR weighs 2 more ounces.
8) FOV - the Burris has the NF beat on both ends = better when hunting/finding targets.
The NF is a good optic, but for the rifle you plan putting it on, I would def go with the Burris XTR 2. I own a couple and am glad I did the switch from what I had (zeiss 4-14, SWFA 5-20, Bushnell 3-21 and a couple older crap scopes). Will be doing a review as lots of people seem to still be having questions about them. I like the price and the features, so I put one on my trainer and a backup match rifle and my wifes match/hunting rifle. I am so far impressed with the ones I have.
Good luck
DT