My Thoughts:
If you have ever been hunting or watched hunting shows, its customary to shoot the heart lung area. It kills the animal, but doesnt always stop it. It can and often does run 100 or more yards before going down.
If you have ever been in a been hit hard in the stomach, you know that it stops you from doing what ever you were doing. How much harder is a stomach shot vs. fist to the stomach.
The goal is not to kill the attacker but stop him from presenting a threat. And stop shooting when that threat no longer exist, anything further isnt self defense.
Two Handed Shooting: Find if you have distance. But most, a huge majority of self defense shooting done at 3 yards or less. The lady who runs the WY State Crime lab often helps with my self defense class tells us the 95+%, from her training and experience is about 5-6 feet.
Presenting the firearm to eye level requires extending the firearm to the point it can be deflected or worse taken.
In my 20 years in LE I had to use my service revolver many times, in controling suspects, building searches, etc etc. Thanking back the only time I remember using two hands is while at the range. You always have something else in the other hand, a flashlight, mirror, door knob, ticket book, and the list is endless.
In self defense it may be your child, wife, or any other person or object you would rather pull behind you to safety or out of the way while presenting your handgun.
I have no problem with two handed shooting but in self defense, I personal think that one handed shooting practice is critical. Not only that, but equal time should be spent training strong and weak hands.