Graham: Get the scope that appeals to you the most, as you'll likely have it and use it for many years, but remember that Leupold's warranty is legendary....for good reason, and the folks who poo-poo it are usually not Leupold owners. Remember you get what you pay for, and the best "deal" now, does not necessarily make it the best choice. Nikon makes very good scopes and other optical equipment, no doubt about it. I own some of their bino's and a digital SLR camera, but when it comes to scopes, well, you know where I stand. In just over 40 years of using their products, I've never had a single negative experience with Leupold.
I have a friend who leaned his rifle up on the rear passenger side tire of his truck in elk camp. About a half hour later he backed his truck up for the evening, and in the process ran over his .338 and Leupold. The scope was toast. He sent it back to Leupold for repair, and in less than two weeks, he had a brand new scope delivered to his home, at no charge whatever, not even for UPS charges. Try
that with Nikon.
If you ever wanted a reticle change, have a ding repaired on the tube, repair scratched glass, have a custom elevation dial laser etched for your particular load, good luck getting Nikon to do any of those repairs or mods, let alone replace the scope when it was clearly your fault. By the way all Leupold Long Range scopes have the side parallax adjustment (30mm tubes).
I'm not bad-mouthing Nikon at all, just trying to illustrate why Leupold is the overwhelming choice of American shooters. Add the fact that they are made in the USA..... Remember, we have choices!
Good luck with whatever you choose.
Fact of the matter is, I've never had a scope of any brand fail the shot. Guess I'm lucky. Have had some problem's with Leupold's returning to zero though. 
) I'm just glad the young lad (Graham) has his new scope, and is all smiles. After all, that's what it's all about!
kb.