I imagine you will get lots of different opinions. Here is mine. The only game you really need a .338 for are big animals -- such as Elk, Moose, Grizzly Bear. These animals at 400 yards probably look about the size of a pronghorn antelope at 200 yards. You don't need high magnification power to target these animals at reasonable hunting ranges. I would think 2x-8x would be an ample variable power range for hunting Elk, Moose, and Grizzly Bear out to 400 yards (consider that Moose and Grizzly Bear are very rarely shot at such long ranges -- Elk maybe more frequenty).

Another thought I would add. I've gotten the impression that scopes take a beating on extreme power rifles. High magnification scopes are probably rarely mounted on such extreme power rifles. I would think that manufacturers may not build the same ruggedness into a 4x-14x scope that would most often find use in varminting rifle set-ups as they would into a 2x-8x scope that may more often be mounted on an extreme power rifle. The kind of stuff that can go wrong is that your cross-hairs can come loose. Imagine that shooting that .338 is like hitting your scope with a sledge hammer along the sight-line and you will have some understanding of the punishment they get. How much more punishment does a .338 administer, for example, than a .30-06 to this scope? than a .243? than a .223?

Eye relief should be a key consideration, as someone mentioned early.