I think it is a given that the 9mm shoots flatter. Smaller bullet at higher speed = flatter trajectory. That in and of itself doesn't mean it is better. Any shooting; long range or short range, rifle or pistol demands that you know where your gun and load hit. Just because one round shoots flatter than another doesn't mean you are going to hit the target unless you know where it hits at that range. If you are interested in this, the best thing to do would be, go out to the range and try it. It certainly couldn't hurt to know where your gun hits at 100 yards or 50 yards. Justifying a self defense shooting at ranges like that would be tough, but it is just another step in mastering your chosen piece and I am sure it would be fun. Everything in shooting isn't about self defense or combat shooting. I often shoot my handguns at longish ranges at junk lying out in the desert. You just sort of walk the rounds into the target by watching the dust fly from the previous shot. When I was a kid I used to take my Ruger MK II and fire the whole mag at a metal target hanging at over 200 yards. We would then wait a couple seconds, and then ding ding ding...... My friends could never do it, but all it amounted to was knowing where to hold, very little skill was involved. As another poster mentioned, ballistic performace is a subject of endless debate, but it is a fact that the heavier bullet will retain more energy over a longer distance.