I'm still deciding on the pros and cons of a zapper, but one
thing I can point out is that your serial port will be generating square waves. Since our bodies live in the analog world, I'd expect us to handle the full sine wave much better than square wave pulses. Also, computer pulses will probably generate irregular shaped patterns. ie. short highs and long lows.
On the other hand, I'm so attached to the computer world, it
might just be my fountain of youth.