The one variable that I DO personally believe is relevant to CCW and HD is safety direction.
IF there is a safety involved in a handgun it should operate in the same manner as any other handguns that might be in your mix.
All of my handguns with safeties are all of the 1911 mindset. I shoot my guns, and my thumb says, "down is off, up is on."
Ever try to turn on a hallway light switch and have to think for a second about it? This thought process does not belong in a self-defense situation.
The lowest paid college major/degree in this country after graduation...
Now, go figure...