I'm a big fan of the 1/7 because it is a "shoot all" at "all ranges" ...lets me shoot the 75's at 300. I won't ever need to do it, but it's fun at the range. I reload 75's.
That doesn't mean the 1/9 is inadequate. In fact, the 1/9 typically shoots the 50-65gr rounds more accurately than a 1/7. Then again, the accuracy difference is insignificant from a self-defense perspective. 1.5" difference in groups won't save your ass.
1/9 will stabilize the 75 and 77gr rounds out to real-world self-defense ranges. People are way too fixated with the idea that they are going to have to shoot at some thug at 150 yards with their ACOG. Just not realistic. Carbine self defense is going to happen at 25 yards and less. At that distance, twist doesn't matter.
One important thing to remember is -- virtually all, if not all cheap bulk blasting ammo is either 55gr or 62gr. I don't know of any 68, 69, 75 or 77gr cheap blasting ammo. I think the cheapest was 75gr PRVI, but that wasn't cheap either. It just wasn't high priced like Hornady TAP.
99% of the shooting you'll do will be with good old 55 or 62gr ammo. Unless you're doing very well financially and can afford to buy and practice with cases of Hornady TAP. Most folks are going to buy smaller quantities to test their firearm with the more expensive self-defense rounds and then an amount they feel they need as magazine stuffers for the SHTF. Reloaders can get the price down to where it's more feasible to practice in quantity.
This removes a lot of the negativity surrounding the 1/9 lately. If you think from a purely practical standpoint, both practice AND self-defense, the 1/9 works. Like I said, you're not going to be shooting anyone at 100 yards in self-defense. Not happening. Maybe law-enforcement will in a stand off situation. Us regular people who are not paid to seek out and engage violent criminals are going to be defending our homes with our AR-15's. The badguy has the element of surprise, and at best you will be defending the interior of your home, or at the very most, just outside it. There won't be any 250 meter down the street shots to fend of wild enraged violent hordes of gang bangers.
Also, too much emphasis on twist and super-bullets. Nothing wrong with getting a faster twist and shooting the most effective bullets you can get. Just consider it icing on the cake. Emphasis should be on skills, not gear. Hits count, not 75gr vs 55gr. Get the best you can by all means, but don't think of it as a make or break deal.
For those guys with 1/9, be happy with what you have. It works. You've already made a quantum leap in effectiveness from using a handgun. Not only in terminal performance, but in the ability to accurately deliver lead. Badguy doesn't care. Shoot them center of mass or in the head with a 55gr from a 1/12, and I assure you their attitude will change in a hurry. Behavioral adjustment will occur.
Even if in some extremely rare case you need to shoot at someone 100 yards away, that 55gr round is going to ruin someone's day. Good old iron sights will work just fine too. I don't think there are many thugs who will have the determination to advance on you or continue the fight after the first blast from your AR. Hit or miss, I'd wager on them RUNNING in the opposite direction. And if not, that's why we have 30rd magazines.