The only actual advantage to subsonics that has been claimed in this whole thread is that they're more reliable. That seems like a pretty sketchy argument to me, but it's the only actual advantage claimed. Other than that, it's just been statements of what subsonic rounds can do, with no evidence or even claims that they're better at these things than more powerful high velocity loads.
If you spent all this effort buying a suppressor, why put supers through it?
I can't claim to speak for the OP, but judging from his post, he's looking for the most effective ammunition he can get for use in a home defense situation, not Hollywood quiet or tacticool.
I consider any heavy subsonic load to be ideal for home defense.
Why?
What would make "any heavy subsonic load" superior to all of the available high velocity loads?
Then why not subsonic 220gr SMK or similar? They'll punch right through light armor (Type I and Type II and possibly Type III-A) since they don't expand and have no hollow point to slow them down.
I've seen .30 Carbine, even with round nose soft points, defeat level 3A soft armor, there's no doubt in my mind that 300 Blackout supersonic loads will do it easily.
Also, why do you consider a bullet that pokes a 30 caliber hole without losing velocity a desirable feature? I think most experts agree that expanding or fragmenting bullets are far more effective for hunting or anti personnel use.
Some will claim that you should use an expanding supersonic load for defense and yet many have fallen to FMJ non-expanding projectiles over the years.
Many have fallen to bricks, nuclear weapons and arteriosclerosis over the years but that doesn't necessarily make any of them the best choice for home defense
I don't have much experience with the 300 Blackout since I just got my first one a few months back, but I have shot quite a few hogs with a 7.62x39 using both supersonic and subsonic rounds.
From what I've seen, higher velocity expanding bullets kill a lot faster and are somewhat more forgiving of poor shot placement than heavy subs.
Either type will work well when shooting a relaxed hog that's eating corn under a feeder. They may not drop instantly, but they won't travel far if hit right.
After the first shot, when they're scared and running like hell, it's a lot harder to place your shots. Even with a well placed hit they don't drop near as fast as a calm hog. This is when high velocity expanding bullets really show their advantages.
They make bigger, more ragged holes that let out more blood, plus they may throw fragments that can tear stuff up well away from the bullets path.
I use subsonics for hog hunting because they're very quiet through a can, don't hurt my ears and won't wake folks that allow me to hunt their land.
I fully understand using a can on a home defense rifle, one shot in a hallway from a HP rifle might cause permanent hearing loss. I don't understand why anyone would want to basically turn their rifle into a .45 ACP with really lousy bullets in a quest for Hollywood quiet. If its a legitimate self defense shooting, why would you care if anyone heard it?
If hogs had guns and the wounded ones might shoot back, I wouldn't even consider using subsonic loads to shoot 'em.
This would be particularly true if they were breaking into my home with the intent to harm my loved ones or myself AND there was a good chance that they'd be high on PCP, crack, meth or heavy painkillers.
I say again, Barnes 110 grain tipped triple shock. Another possibility would be the Nosler 125 grain accubond. Both of them should give excellent terminal performance and good penetration through intermediate barriers.