While I wish your friend a speedy and full recovery, that injury screams of him having put his finger on the trigger when holstering or un-holstering his Glock. Manual safeties are no substitute for being well trained and mentally alert (and always following the 4 cardinal rules of firearms safety). Of course something else may have engaged the trigger, like a thumb strap. But again, that is covered with training and mental alertness. As I say in training, there are NO accidental discharges only negligent discharges. That being said, if you feel better with a manual safety by all means get an M&P with one or have S&W put one on. You may also want to consider getting Apex's kit for duty guns that increases trigger pull weight.