With just a handgun, double tapping, or shooting till the threat goes down is usually not effective against more than two assailants. You just probably won't have the time, to shoot them all more than once, if its a full on assault. If its five people, all trying to harm you at once, you'd be lucky to shoot all of them one time each, before you were disabled. With two assailants it might be possible to have time to double tap both of them, but you might not. So 8 shots, ready to go and one or two speed loaders would be as good as a 1911, or a Glock 21, etc against multiple assailants.
In the end, it really comes down to, do you shoot as well with a N-frame revolver, as you do A S&W M&P, Glock, etc, etc. Do you like it better, its that simple. If you are happy and confident with a 627, then I think it would be plenty of firepower in most handgun SD situations.
tl;dr Can someone take out a five man hit squad with a 627? Probably not, but probably not with any other type handgun either.
"No free man shall ever be debarred the use of arms."- Thomas Jefferson