If you talk to people who have been in firefights you will find some interesting information. The likelyhood of you actually hitting your target where you intend is very low. In a firefight you lose all fine motor skills, you will get tunnel vision, your adrenaline will be pumping, and if your target is on the move then you may not even hit it.
Talk to some police officers who have been in firefights and see how many shots they fired versus how many if any actually hit their targets. Some military Combat Arms Instructors put it this way. Say when you qualify with an M4 out of 40 shots, you hit 23 (which is the minimum the Army requires to qualify). If you can hit a stationary target, under optimul conditions, 23 times from the prone position then you translate that to a real world fire fight you would be lucky to actually hit your target even once.
So I say regardless of what your situation is if you can hit your target with a controlled pair in the chest and they are still able to move and you are confident to hit them in the head then go for it. However, the likelyhood of you missing and injuring an innocent bystander is much higher than you hitting them in the head where you intend.
Sig P226 .40, Mossberg 500 Persuader, Springfield 1911 GI, M91/30