Interesting question.
Let's examine a few "knowns" and then try to extrapolate some possibilities.
We observe with the .223 round that it has a minimum effective velocity below which destabilization and fragmentation will not occur upon penetration into a target.
This destabilization is caused when the bullet experiences a change of medium - that is, when transitioning from the medium of air to the medium of flesh.
The higher the velocity, the more likely the bullet will destabilize.
The lower the velocity, the less likely the bullet is to destabilize.
We also know that the faster the twist rate of the barrel, the faster the bullet will rotate when it leaves the muzzle.
For a hypothetical bullet travelling at 3,000 feet per second, it would rotate at 5,143 revolutions per second or 308,580 revolutions per minute in a 1:7 twist barrel, and only 4,000 revolutions per second or 240,000 revolutions per minute in a 1:9 twist barrel.
Now for the conjecture.
Maybe if faster velocity means better bullet destabilization upon impact, then higher rotational speed may also result in better bullet destabilization upon impact.
If so, then the effective range of any given bullet/barrel combination could be extended by using a faster twist barrel. In other words, as long as the bullet is stabilized by the barrel, then the faster the twist the better - 1:7 would be better than 1:9.
BTW: I'm not covinced that "overstabilization" is real. I do believe that if one shoots 40gr varmint bullets out of a 1:7 twist barrel that the bullet may self destruct due to over rotation, but any bullet used in a defensive scenario (i.e. 55gr and above) shoots just fine in a 1:7 barrel.
Stream of consciousness mode OFF.