Rich what is your snake room temps? How much variation do you have daily and summer winter? I see 7 or 8 degrees day/night and 25 summer/winter. Please do not tell me that under those conditions you do not see spikes with any and all on/offs. You do, I promise you, what I posted was in UNSTABLE room temps. They work great in reasonable stable but when it gets cold the probe responding every second is too bloody slow. I used to see spikes up in the 100-110 range and lows in the 82-5 range it simply does not sample fast enough to prevent the cooling and then over shoots trying to get the temps up. Proportional units are more versatile under most conditions they sample many times a second and are able to adjust.

You can speak for your self that is fine, But do not tell me that it works on my rack. 30º ups and downs I cannot live with and unless you have 23000 you want to give me I can't pay to get the bloody seaweed out of the walls! I qualify my statements you have made blanket sweeping statements about conditions you (as you mentioned in other posts) do not have.

On/Off types do not do will in unstable (cool) room temps. Don't take my word for it try it! Stick you rack in a 60ºF room and tell me what temps you have. My herpstats do a amazing job at keeping all three temps perfect (ambient air, warm, and cool) My Johnson did not.