I've owned one for about 10 years now, mine is based off a New Haven SS Model 70 action and I have taken coyotes, wolves, whitetails, mule deer, black bear, elk, moose, and grizzlies with it. The game has been taken from between 30 yards and 525 yards.
I would not say there is a meaningful difference in ballistics or ability of a given cartridge to kill from say 280 Remington on up to the various 375's. It has been my observation that one's shot placement has far more effect on killing than the cartridge in the range of cartridges I mentioned. And for that matter you could include the 270, the 6.5x55 and a few others. I also think the term "flat shooting" with respect to bullet drop is over used and not understood that well. Out to 500 yards there is not a meaningful difference in bullet drop between the venerable 3006 and all of it's offspring, the 308 and it's kin, the 338wm and it's kin, and a number of others I won't bother listing but it would include all of the fast 30's.
I also shoot a bit with it through the year to stay sharp. Free hand to 200 yards and with a rest to 500. After some experimentation I settled on shooting only 250 grain partition style bullets for uniformity in POI. It has been my experience that using a 180 for deer, and a 200 for elk, and 225's for moose and 250's for bear, etc, is too much for me to keep track of - by using one good bullet I can be more effective at the ranges I have chosen to shoot at.
One thing I have found with respect to meat damage is that the 180's out of a 3006 or 250's out of a 338wm bloodshot meat a heck of a lot less than the fast 30's, the 7mmrm, and others in that velocity class.
In summary I would say one does not "need" more than a 3006 class cartridge for all of North America, but having said that if a guy wants a great all around rifle with a bit more wackem at distance the 338wm is a fine choice. And Model 70's are, in my experience, a uniformly fine rifle.
Hope this helps.
