OK, if I may present a (surely) controversial opinion--ready as I often am to change my mind to persuasive arguments:
I've never quite been sold on the need for 300 magnums. The African hunting world seems to have done quite well without Roy Weatherby in the '40s and Winchester in 1963--by which time hunting in the Dark Continent was well past its golden age. I know, besides the obscure .30 Newton, there was the .300 H&H introduced in 1925 (IIRC), but its ballistic advantages over the old '06 are so slight as to reinforce, rather than refute, my opinion.
From most ballistic tables I've consulted, the .300 WM shows meaningful advantages over the '06 only past the 450-500 yard mark. Also, I've never been a believer that kinetic energy transferred to the animal has any significant impact on killing power, so energy figures--as long as they are above a reasonable plateau for humane killing--don't play as important a role in my mind.
Although in my younger days I had been a sucker for the nostalgia and good looks of the .300 H&H, were I to go .30 cal now I wouldn't hesitate getting an '06--and I don't think I would miss at all the pyrotechnics, added recoil, and cost of a .300 Magnum.
I know I'm the minority, so I must be missing out on something. Will a lifetime of hunting without a .300 Magnum be one of the many experiences I'll regret when on my deathbed?