As John3200 said, striker fired pistols like the M&P function very much like revolvers. That was one of the selling points when Glock started marketing their firearms to LE agencies. The transition from revolvers to Glocks would be much easier because Glocks were like revolvers in that there is no active safety device in either.

What prevents accidental firing of an M&P is what prevents accidental firing of any firearm. Know the four rules and follow them. Plus, don't leave firearms where kids or other untrained people can get them.

Get what you are comfortable with, but any safety device can be defeated, even by a 5 year old. Safe handling and storage are the real safety devices.