Each student faced a target at a distance of about five yards, with his or her handgun fully loaded and holstered. Standing behind the student was an instructor with a 50,000 volt stun gun. The instructor applied the stun gun to the student's arm, leg, or back. The shock of the stun gun was the signal for the student to draw her handgun and to empty it as quickly and as accurately as possible.
Although the reactions of the students varied, all were able to quickly draw their guns and deliver multiple center-zone hits. Hundreds of students have successfully completed this exercise. While the stun gun did hurt, it was not incapacitating. To be effective, the stun gun, a contact weapon, must be held in contact with the assailant for a number of seconds, or he must voluntarily break off the attack.
Various stun gun manufacturers are coming out with new units with ever increasing claimed voltage. They still suffer from the traditional downsides, the principal of which is the necessity of having to hold the unit in contact with your assailant for as much as 5 or 6 seconds, during which time he will not exactly be cooperative. Other factors include battery strength, voltage, and the fact that you must be close to your attacker.
There is a new generation of Tasers that have recently come onto the market. Law enforcement magazines and first person reports have been very positive with respect to the effectiveness of the new higher wattage tasers. While the "older" models had outputs in the 5 to 14 watt range (probably used in the much publicized Rodney King incident), these new devices have outputs up to 26 watts. Note that there are civilian and law enforcement versions. For instance, one Taser manufacturer limits civilians to their 18 watt model having a range of 15 feet, while the LE version's specs are 26 watts and 21 feet.
There are many variables affecting the efficacy of these devices, including model, wattage, contact time, battery strength, and so on. The taser must be aimed at, and hit your attacker. You only have one, or at most two, sets of darts in a taser.
Based on our experiences thus far, we are currently unwilling to entrust our lives to either device.