Electronic ballasts are much quieter and generate less heat than magnetic. I believe that the heat is wasted energy, thus the electronic ones should be more efficient than magnetic. That being said, the magnetic ballasts tend to drive bulbs a bit harder than the electronic ones do.
I have used the Advance M57 but didn't provide sufficient cooling and fried the capacitors in about a months time. In addition, those things buzzed like mad! :shock:
I've been using the Coralvue Electronic Ballasts for over a year now and am extremely happy with them.