MC,
I'm not sure which side you're debating for. Smaller/faster or bigger/slower. But yes, energy does matter. While mass and velocity are "cohabitants" in terminal ballistics, they are not mutually exclusive. That's why the 45 and 300WM is not a fair comparison. But when penetration is desired over hydrostatic shock, bigger/slower, solid/harsdcast is the winner. And you, Art and I know that a big hardcast right behind the shoulder is not always, but usually, a very short tracking job if it isn't DRT. It also equals more clean meat and less hamburger.
I'm not arguing FOR either approach. I'm saying both work via they make enough energy. Each approach has its merits and weaknesses. If you have shots across open canyons at 350 yards, you'll probably be biased toward the smaller bore, higher velocity gun with the high ballistic coefficients. If you're hunting woods like I am now, you might want the benefits of that big bore gun. As you say, less hamburger, more undamaged meat, and a GREAT hole to put blood on the ground. Either approach will work in the woods, but across those canyons the high velocity approach is my preference. Not saying a .50-110 can't shoot 400 yards. Hell, that shot at Adobe Walls was what, a mile? Probably a LOT easier with the HV rifle, though, and more ethical to try.
So, you see, I'm taking both sides of the "argument". I see the merits and weaknesses of either the big bore/slow or the small bore/fast approach. I'm not really a fan boy of either, like owning both. Closest thing I have to a big bore cartridge rifle is a .357 lever carbine. I've thought of getting a .454 or a .45-70, but there ain't nothin' around here I'm that mad at.
That front stuffer is WAY cool, though, and I enjoy hunting with it even if it IS in rifle season.
I think of it as a modern rifle, just slow to load.
BTW, the old standby with magazine writers was always 1000 ft lbs minimum on deer, 1500 on elk. Well, with a big bore gun, I really don't think that's accurate. You can probably drop down to 800 for the big bores if not a little less. I totally have no proof of this, it's just a feeling I get from hunting with both and with handgun calibers. Don't ask me to prove it 'cause I can't. It's JMHO.