500 ft/lb's of energy versus 600 ft/lb's won't make a lick difference to a medium sized game animal,
I completely disagree for at least two reasons off the top of my head. First, the difference between 500 and 600 ft. lbs. does make a difference with humans at typical self defense distances. How do I know this? A study of 1,800 bodies shot in gunfights tracked how often a caliber did NOT immediately incapacitate an attacker. These are actual bodies and not gel tests or meat targets. The results for the calibers tracked were as follows (i.e. percentage the round failed to immediately incapacitate):
.32 ACP - 40%
.25 ACP - 35%
.22LR - 31%
.38 Special - 17%
.380 ACP - 16%
.45 ACP - 14%
.44 Magnum, .40 S&W, and 9mm - 13%
Shotguns (80% 12 gauge) - 12%, again, shotguns can over penetrate and spend their energy.
Centerfire rifles, .357 Magnum, and .357 SIG all tied at 9%. Again, centerfire rifle rounds often overpenetrate and waste energy.
.44 Magnum didn't do any better than 9mm because, as one medical examiner stated, he never saw a .357 Magnum leave a body and he never saw a .44 Magnum stay in one. When we're talking about pistol rounds in particular, a .44 Magnum pass through human bone and tissue so easily that almost half its energy leaves along with the bullet.
As a trauma room surgeon stated, a bullet that stays in the body is typically more damaging than one that leaves the body. And more germain to the point, a study conducted at West Point concluded that a body hit with more than 500 ft. lbs. of energy is more likely to be instantly incapacitated than a round below that threshold, and they made the estimate based on experiments by Chinese scientists shooting dogs in the rear leg (and thus instantly shutting down their CNS via hydrostatic shock) and American scientists who did the same with swine.
Now a human-size wild animal is a lot more resilient than a human, which is why deer and other game have been known to travel a long distance after being shot with a lethal wound.
We also have to consider muzzle energy vs the energy that makes it down range if we're handgun hunting medium sized game up to 50 yards with a handgun.
Since we're not dealing with rifle velocities and energy, certainly handguns are comparatively marginally powered. But if canine and swine experiments help scientists predict a >500 ft. lb. threshold increases a cartridge's incapacitation rate on humans, it's extremely likely a difference of 500 to 600 ft. lbs. might make a difference on deer at 50 yards.
A round that has 548 ft. lbs. of muzzle energy, for example, may only have 464 ft. lbs. of energy at 50 yards. A round with 650 ft. lbs. of muzzle energy, however, might still have 525 ft. lbs. of energy. Those are the ballistics of Hornady's [underpowered] .357 Magnum and 10mm XTP hunting rounds respectively. A .357 Magnum round warmer than anything Hornady, Federal or Winchester offers however (like a Buffalo Bore offering), might have 675 ft. lbs. of muzzle energy which maintains 567 ft. lbs. at 50 yards. An Underwood full-powered .357 round starting off with 770 ft. lbs. of muzzle energy might fair even better.
The point wasn't the difference between 500 and 600 rounds anyway. My point was that .357 Magnum cartridges loaded to their full or near full potential can far exceed that which, in my opinion, could make "a lick of difference." If broad-side shots with a pistol are recommended, then it stands to reason any advantage you can gain from a hotter .357 Magnum or 10mm cartridge is welcome, especially when it's useful for a bullet to pass through the other side of the animal to make a blood trail more patent.
That doesn't matter for humans, but it does for game. If a bullet leaves the body with hardly anything left in the tank, you can get both maximum effectiveness and a blood trail (for a handgun caliber; rifles have so much more energy there is no need to be concerned about the bullet staying in the animal because of the desire for a blood trail and preserving as much meat as possible [it's obviously better it leaves]. If you hit the deer in the shoulder bone, for example, you might not do as much damage as you'd like to the lungs. So in some situations a hundred foot pounds of energy likely does make a difference in my opinion).