I tried the electric fence and quite like it, much easier to implement. One thing i did to reduce power usage was to build a light sensor so that the fence only turns on at night when mobs spawn. Hooked up a solar cell to a bat box putting a detector cable between the two and a heavy drain on the box so it will charge all day, 4 or 5 illuminators will do it. You can then use the red stone output on the detector to control the fence power using a splitter cable.
This cuts power consumption in half making a large network much more manageable. The problem i have is that there are still a few mobs around in the morning when the fence shuts down.
