Makoman:

Three things to think about.

(1) Most magnums are mounted with scopes with magnification in the range 3.5-10x or lower. It may be that you may experience trouble with more powerful magnifications on your magnum. Leupold will cheerfully fix you up, but this may not rescue your hunting trip!

(2) There is a trade-off to get the higher end magnification: your low end magnification gets higher, and this may diminish service you may want at the low end of magnification, for example hunting elk in dark timber after the elk have gotten wise to the rifle season and are hiding out.

(3) Given the specific parameters you mentioned, your scopes may be dimmer than an otherwise equivalent 3.5-10x 40 mm scope. The typical calculation is to find an exit pupil diameter by dividing the diameter of the objective by the magnification. The bigger the exit pupil the brighter the scope, to a maximum of around 5 mm.

If I were you I would optimize the scope for the most typical hunting conditions I expect to encounter. Also, there is some comfort in buying the most popular equipment variation because the equipment is more thoroughly tested in the field by all the other purchasers of the equipment. Any troubles are quickly discovered and ironed out (provided you buy from a reputable manufacturer).