Any preference between a Warming Tray and an Immersion Heater? Is one easier to deal than the other? Relative Temp. Accuracy? I will need to get the temperature in the Dev. tray at 72F, Toner 79F and sometimes 100F (Nelson Gold). A tray inside another tray is not an option because of space limitations. I've seen some threads on this but wonder if there is some information that is slightly more up-to-date. Thanks.