Golden, I don't deny that 147gr bullets penetrate farther than 124gr or 115gr bullets. What I was saying is that the currently available defensive 147gr JHPs (like Golden Sabers) don't show massive overpenetration with no expansion or deformation.
As you say, the original hollowpoint 147s didn't have a cavity for expansion, but for accuracy. I didn't know that, but it would explain why early 147gr hollowpoints developed a reputation for going straight through a target without deforming or expanding.
Tests using 147gr JHPs that are meant for defense and designed to expand even at subsonic velocities show consistent expansion in gel. If the bullets do end up leaving through an exit wound after that, they are severely deformed and significantly slowed.
I don't know if the gel in the tests I saw was properly made or calibrated, but 147gr Remington Golden Sabers showed 14 inches of average penetration, and WWBs showed slightly less.
The "fast and light" vs "slow and heavy" argument will go on, probably forever. If you prefer to use 115 or 124gr defensive rounds and you shoot well with them in your carry pistol, then by all means, you should keep carrying what you and your gun like. Any high-quality defensive 9mm JHP should effectively ruin an attacker's day.
I personally use "slow and heavy" defensive ammo, but to the .45ACP fans, even my 147gr 9mm JHPs are considered "mosquito stings," because they're not slow and heavy ENOUGH!