Inukshuk,
It really depends on your target and the ranges you will be shooting. Obviously on the tundra there is potential for some lengthy pokes.
TO be honest, for game in the 300-400 lb range, that would really be far more glass then you really needed unless you were shooting past the 800 yard mark which the '06 is certainly able to do in an accurate rifle.
Question is what is the range that the vast majority of your shots will be at? I have used 15x to snipe chucks at +1000 yards. Getting a quality shot on a deer size animal at this range with the same 15x is very easy.
If your looking to hunt at 800 yards and less, I would say for the money, get into something a bit less bulky for your '06. The quality is certainly there but I am not sure you need to put that much into a scope for the rifle you are using.
That said, I personally feel, as long as the magnification power does not adversly effect you shooting the rifle, there is no such thing as being over scoped, but to be honest, it would be easy to spend 2/3rd the price of the big IOR and get a scope that would easily perform to your highest expectations.
If you want a very top end scope I would look at the 3.5-15 50mm NXS nightforce or the 5.5-22 50mm model. About the same money but will fit your rifle much better with the ability to mount the 50mm much lower then the 56 mm.
Good Shooting!!
Kirby Allen(50)