My overall take on this is that most JHP manufactured after the mid-1990's is better at reliable expansion, even through barriers. The FBI Protocols had become the Holy Grail for manufacturers looking for LEO bids.
I don't buy new ammunition every month for SD. I buy it by the case, and use it up slowly. If an ammo was "the best" in 2003, it will still be a good performer in 2012. In fact, the manufacturer has probably tweaked it along the way to improve performance.
Collapsing a JHP makes it perform just like an FMJ, by the way. So, plugged solid, or collapsed operate in the same manner.
In the early 1990's we did some bullet testing in an apartment project slated to be torn down. It had been a new Section 8 Housing, built in the 1970's, and treated in the normal manner by it's inhabitants, poorly.
We fired through interior walls with various ammunition, in 9x19, .380 ACP, .22 LR, and .45 ACP. ALL of them, JHP and FMJ penetrated completely through at least the following room, with one exception. The 9x19 Glaser Blue penetrated the first wall at caliber size, the next wall, about 4" away in a blast about 4" in diameter, but failed to penetrate a woman's summer shirt on a hanger one foot behind that wall.
ALL of the JHP expanded at least minimally on it's way through multiple walls. Some had wall-board embedded in the cavity. FMJ just kept going until it's energy was expended. Usually another two walls beyond the JHP.
Later, we came back with a 6" Model 29 S&W. It's 240 gr JHP penetrated the walls of three complete units, struck the outer wall of brick, and knocked the brick loose, and onto the ground. The bullet was obviously expanded, but mangled by the brick.
I am a CCW holder, and go about armed. I am certainly less concerned about penetrating auto glass, sheet-metal, plywood and wallboard than an LEO. If any of those barriers are between me and the attacker, I intend to use them at first opportunity to dis-engage and let the police handle the rest of the shoot-out.
Most of us will face an attacker in dim light, at distances of less than seven feet. We will be presented with frontal shots upon unarmored targets. Those are the statistics.
If you intend to be in combat against hordes of weight-lifting druggies, carrying automotive windshields or 1" thick plywood shields, arm yourself accordingly. My choice would be a Heavy-Weapons Company of Marines.