Have written pretty extensively about this in the Back When...off-body carry mandates that you be willing to go to the gun sooner than you would with the gun in a holster. Ideally, off-body carry allows you to go to the gun with some stealth, as does the SafePacker. My "ready" position with the SafePacker is something like this:
1) SafePacker stablized with left hand.
2) Unlatch SafePacker and insert hand.
3) Get a good firing grip in the gun.
4) Smile, smile, smile
Michael B