SuperRuger,
I'd like to know from where you get your information about the .45 ACP and it penetrating "only about 2 inches" or being "too weak" to be an adequate SD round. What you seem to be claiming doesn't make sense to me nor does it jibe with my experience.
I suspect you've read and taken to heart information from
Handgun Stopping Power by Marshall and Sanow. I've disagreed with Ed Sanow since the late 1970's when he first began publishing his opinions in gun rags. Ultimately, he's unquestionably biased in favor of the lightweight/hi-speed bullet theory.
The .357 Magnum, Remington 125gr JHP @1393 fps penetrates approximately 14.17 inches in ballistic gel for testing. Expansion is very good, opening up from .357" to a measured .708".
The .45 ACP does nearly as well in many cases, depending on the type of projectile and load. For instance:
.45 ACP Federal 230gr HydraShok JHP - 12.9" average
.45 ACP ProLoad 200gr
+P Tactical JHP - 13.2" average
.45 ACP Remington 185gr
+P G.Saber JHP - 13.9" average
.45 ACP Winchester 185gr Silvertip JHP - 9.6"
.45 ACP Federal 165gr Hydra-Shok PD JHP - 9.5" average
Expansion in these .45 ACP loads averages .67" with the exception of the Winchester Silvertip load which expands to .75"
As far as the guns themselves, if you do a fair apples to apples, give me the 357 mag. Still today by most experts considered the gold standard for personal defense.
In that case, compare the .357 Magnum from a 6-inch revolver versus the .45 ACP also from a 6-inch revolver. Using a S&W 27 vs. a S&W 25 should be "fair" - both are large "N" Frame revolvers, both are six-shooters. Both weigh in at a nominal 44 and 46 oz respectively, with a long barrel.
.357 Magnum - 125gr JHP @ 1450 fps (adv) = 6.01 ft-lbs recoil
.357 Magnum - 158gr JHP @ 1240 fps (adv) = 6.81 ft-lbs recoil
.45 ACP - 230gr JHP @ 830 fps = 6.24 ft-lbs recoil
.45 ACP - 185gr JHP @ 900 fps = 5.03 ft-lbs recoil
.45 ACP
+P 185gr JHP @1033 fps = 6.25 ft-lbs recoil
This puts the .45 ACP out ahead with a larger hole, less flash/bang, over 90% of the same penetration, and higher numbers in "relative stopping power".
If we believe the numbers at the website you provided, then the best the .357 Magnum manages on the relative stopping power (RSP or "Hatcher" scale) provided, is 63.88 using a 165gr bullet at 1290 fps. Unfortunately, the .45 ACP 185gr +P at 1000 fps rates 72.2. Even the 230gr LRN .45 round rates a 68.1, making it "better" than the best .357 load.
The problem here is that we seek in vain a mathematical formula to describe the likelihood that a particular round will stop someone with a single hit. But there is no accurate way to mathematically model the person's determination to survive, the effects of drugs/adrenaline on his system or even to factor in his body-mass-index (fat ratio). All of these may play a part in determining whether he is stopped or continues to pose a threat.