I also have the Testo 510 although we're using the dual input uei manometers in school. They seem nice, feels solid with nice rubber boot and strong back magnet. I kinda like it but I also like how small the testo is and can fit in my bag easily without adding more weight to it, just wishing the back magnet was a little stronger.
Which makes more sense to you? CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10% ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%