I don't understand the infatuation with stun guns. They only shock the bejesus out of for as long as they are in contact with you. Yeah, the fat guy above slammed his head into the wall, but in reality tasers work because they contact and maintain contact. If you've ever been where someone was tasered, as soon as the power turns off, the person is getting up. I think that is the reason people get train tasered, cop sees them get up and hits them again instead of cuffing under power.
I just don't see it as an effective self defense option unless you use that 2-3 seconds for a head start. I'm old and slow, 2-3 seconds isn't going to buy me much time if that is my only option.