So to limit myself to Learningman's actual request, I submit the following;
The 7mm RUM will likely never achieve the popularity of the 7mm Magnum or for that matter the .300 Win mag. Simply put, the flattening effects (2-4" at most reasonable ranges) on trajectory by increasing velocity come at the cost of much greater powder consumption and little if any increased terminal effect. Sort of like the Weatherby's, sure they are faster than just about anything in their respective class but they really can't do anything noteworthy compared to the more "common" "standard" cartridges.
A substanitive reason to avoid the whole "Ultra Mag" thing is that the brass can't readily be formed from existing cartridges which means that when they fade from popularity, you'll be royally screwed as a handloader/shooter.
What is unclear at this point is what would you consider your maximum range? The continued nonsense about B.C. as it applies to hunting rifles that are most frequently used at sub 200yds is not a meaningful to just about all hunting cartridge debates. Yet when you stated "really out there" shots it leads the debate towards truly long range shooting (600yds+). At this distance, the retained energy of the bullet will preserve velocity at range. The two most influencial factors in evaluating would be the B.C. and the bullet weight. Given that you'll be using hunting bullets, the BC WILL SUCK and once again, is a pointless measure in hunting cartridge debates. So now you're down to bullet weight where the 7mm falls short compared to 30 cal and 338 caliber offerings.
The thing that most high velocity minded folks ignore is that higher velocities only change the trajectory curve by a few inches, if you're taking a long poke you'll still have to compensate for range. Most if not all shooters can't honestly determine if they held that 2 inches lower or higher on their target. Nearly every cartridge vs. cartridge debate staged the situation in favor of the higher velocity round by making the zero for the magnum farther than the standard. The they talk about how the standard has dropped several feet at 300 yards whereas the magnum is going strong only 100 yards away from it's zero. Yet when compared with equal zeros the difference is unispiring, especially when you consider it costs 30% more to shoot the magnum.
