Testing projectiles and predicting their terminal performance, has been an accepted science for over 20 years, and used by every major military and law enforcement organization in the country. The results continue to correlate with field results. Unfortunately, some folks still prefer anecdotal stories, gun magazines, fictional street shooting
"studies", and internet bloggers, but those numbers are dwindling. Much to the consternation of those who financially gain from promoting junk science and whiz bang ammo in their magazine articles and blogs.
Speer has a load comparison tool on their website. You can choose various loads and then view them side by side.
The best .40 and 9mm, penetrate and expand similarly. That is how pistol bullets work. Not through some kind of mumbo jumbo.
Comparing other manufacturers products legitimately tested, will yield similar results.
Bullet technology has continued to improve, and the benefits .40 offered 20 years ago have diminished. The slight
.40 loads give over some
9mm loads, is arguably not worth the penalty in recoil, lowered capacity, and increased cost.
That fact is becoming clear to those who study the subject, and it's why some agencies have converted to .45 from their .40's, to get real
improvement, and why some have gone back to 9mm, and more are making plans to.