i like my double ranco setup. its an on/off system but i've heard that on/off tend to save electricity (not sure about that, its just what i've heard).
sometimes you dont need a thermostat with under tank heaters like zoo med. i like using ultra therm heat pads though because of the quality. with ultra therm, i would recommend using a good thermostat though.
hope that helps. i would wait to hear from others as well, as this is only my experience and others could have much different outcomes and opinions.
I have been really happy with my Herpstat. Just ordered a Herpstat II for new setup. They are really easy to use and super reliable. My temps have been perfect for last 2 years and I have not had to touch the thermostat.