I am a huge fan of the 340 wby. I've shot a number of different mark V varietys and all were 1/2" to 3/4" shooters with factory ammo. Weatherby ammo is unusual in my experience in that it nearly always chronographs at advertised velocities. While the 338RUM clearly has case capacity advantage, in factory ammo, the loads I have seen chronographed were within 50 fps of weatherby factory ammo--not much of a difference. If weatherby rifles fit you well, I would strongly encourage you consider that route. I too have contemplated adding a 375RUM to the safe. The problem I have is here in North America, I don't know what it could do that a 340 with 250grain bullets at nearly 3000fps couldn't do better. While it does have the ability to shoot commonly available heavier bullets, I thing the greater sectional density of the 250 grain .338 bullets at higher velocity will always out pentetrate the 375RUM while doing so with a much flatter trajectory. In addition, 210 partitions at 3250 fps make one hell of a long range elk/moose/caribou and black bear load--they've also worked suberbly on anterlope and whitetails (although clearly overkill). I've come to the personal conclusion that the 340wby may be the perfect all around rifle for North American big game.