Hi,
It seems DGW's point about property defense laws is very important in one's choice of arms, ammo and accessories. In CA, for example, we can use deadly force against a BG if we perceive him to be a threat to our life or the lives of others, inside the house, and in certain cases, outside the house. We cannot, however, use deadly force to protect property as far as I know.
So for places like this, home defense is going to be a very short range proposition. I once saw a discussion with the mfr of a small carry pistol which had virtually no sights (a little nub at the end of the barrel perhaps), and the mfr was asked why no sights. The answer was that in the typical self defense scenario, that proverbial "7 yards" distance we've all read or heard about, the shooter should be familiar with his firearm well enough to be able to point shoot something the size of a human, even keeping the shot to center of mass, without the use of sights at all. Interesting point.
For other places, it sounds like one should research their laws, then make the decision based on what they're allowed and what kinds of situations could occur. For example, if one's got some acreage, a 100-200 yd shot sounds quite plausible if defense of property is allowed. But it's hard to get over 100 ft outside on my postage stamp "city" lot of 8000 sq ft, and hard to get over 25 ft inside the house. In other words, what are the parameters we need to know to answer the question?
Rick C