I could hardly agree more with your comments on bullet weight and diameter in relationship to on game performance. Frontal area is a HUGE factor that many fail to figure into their equation for choosing a cartridge for big game hunting.
If I have a customer come to me and say they want an elk rifle, first thing I ask them is how far do they want to shoot. For conventional ranges, 500 yards and less, a well placed bullet from really any caliber 7mm or larger will be extremely effective.
WHen you start pushing the 1/2 mile range, I really start to recommend AT LEAST a 30 cal magnum. There is no question that lesser rounds will work or smaller 30 cal rounds, that is not the point, I want to recommend something that will work if things do not go just right.
For those that want legit 1000 yard reach on elk, I ALWAYS recommend a 338 magnum.
All that said, not all cartridges can be lumped into their labeled caliber family and be considered all equal. For example, my 7mm driving a 200 gr ULD RBBT to 3300 fps can hardly be compared to a 7mm Rem Mag with a 160 gr Accubond at 3050 fps. Apples and Oranges. My 7mm has been used several times on elk out to and past 1000 yards with excellent results.
Still, if someone wanted me to build them a dedicated 1K elk rifle, I would recommend a 338 magnum over my much more ballistically impressive 7mm.
For heavy game, I would rather give up a bit of ballistic performance for better terminal performance.
But I also fall back on my original comment, you put a quality bullet in the vitals at any range where the bullet has enough retained velocity and energy to provide proper bullet expansion and performance and you will be punching your tag, no matter what the caliber is, AS long as the bullet and chambering are appropriate for the game being hunted.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Farther, Faster and Flatter then ever before.
Web Page: www.apsrifles.com