From what I understand, the main issue with +P+ ammo is that there are no actual standards for it, and it can be of excessively high pressure, but with minimal benefits, and (as you mention) some downsides.
Again, from what I understand, standard velocity ammo often (and counter-intuitively) has better performance than the higher velocity +P stuff.
As mentioned above, I believe the most ideal 9mm SD load is probably a standard velocity 147gr (through a sufficient length barrel).
But, all that being said, I wouldn't succumb to the urge to overthink this. You would be very well defended with any of several brands of modern HP ammo, in any weight from 115 to 147, whether +P or standard velocity.
I'd go with whatever was conveniently available, most economical, and cycles reliably in your SD pistol.