I don't doubt the damaging potential of anything coming out of a shotgun barrel, especially 12-gauge. And I'm just a theorist -- never even fired a shotgun until last couple years, and then just some skeet and target range.
Most research I've seen, ranging from well-meaning guys on their farms to technical studies for law enforcement, does not recommend birdshot for home defense. However, it's certainly wise to be skeptical and alert to nuances for a person's particular environment and needs.
I agree it's ironic that many people are looking for reduced recoil (including .38 and plus loads in .357s) when maybe they should just be buying a smaller caliber gun in the first place.
For example, I considered 20 gauge, but when I discovered my Stoeger coach shotgun is the same size and weight in 12 gauge, I figured the best buy would be the 12 gauge and then tailoring whatever size ammo I found best for me.
Likewise I'd rather have a slightly heavier .357 with the option of shooting plus or .38 than having only a .38 revolver.
I'm also intrigued by several shot damage assessments pointing out that many targets are not engaged head on as on a target range. Shots hit from different angles such as to the side rather than head on, and extra impediments such as heavy clothing and raised arms and weapons often further reduce load impact.
And of course in stress situations many shots do not hit well at all. So better to have the most potent load that is comfortable to shoot.
Many birdshot advocates seem to be including some birdshot shells in mixed loads in their pump shotguns, e.g., couple birdshot, then some buckshot, maybe even a slug. Since I use only a double barrel coach shotgun, both my shells and their backups have to be buckshot, in my opinion.
I'm still going to try some 12-gauge low recoil options. Finally located some 1 3/4 Aguila Minishells (seven No. 4 and four No. 1 duplex load) and some Winchester 00 reduced recoil. Will try first to get them locally. Might be winners for my needs if they're still reasonably effective and as pleasant to shoot as the Winchester low recoil / low noise No. 8 birdshot.