I put a Crimson Trace on my S&W 640 a few years back. I like it and I like that it tells you when its time to change the batteries. When the batteries are running down the laser will start out bright and then slowly fade. Once my Gun starts doing this I change out the batteries even though I could probably get another 6 months from them.
Shot placement is everything! I would rather take a round of 50BMG to the foot than a 22short to the base of the skull.
all 21 of my guns are 45/70 govt 357 mag, 22 or 12 ga... I believe in keeping it simple