I have two Hydor ETH 200Ã¢â‚¬â„¢s. Both hooked up to Ehiem 2215Ã¢â‚¬â„¢s. One is on a 55 gallon and the other on a 30 gallon. I canÃ¢â‚¬â„¢t tell you how good the thermostats are, because I have them hooked up to temperature controllers. But, I can tell you they both do a fine job of holding the tank temperature where I want it.
I have a ETH-200 inline on a Eheim 2217 on my 55gal and a ETH300 inline on a Eheim 2217 (soon to be inline on my FX5, have the parts just have to make it happen ) on my 90 gal. On my 90 gal. im also using a Hydor Hydroset digi thermostat to control the ETH300.
They work great so far but *** only had them for a few months.