I've been using a Therminator for 3 years now with zero issues. No clogging, no nothing. I've pushed well over 100 batches through it. IMO, it was well worth the money I spent on it. Like anything in life, you get what you pay for.
In comparison with the Shirron chiller, it has quite a bit more effective surface area, so if your cold liquor is cold enough, you can push wort through it pretty quickly. In the wintertime, my ground water is cold enough for me to knock-out 15 gallons in 10 minutes to 63-65 degrees. To note, I do use a pump to push wort from my boil kettle through the Fermenator to my conical. I have not personally done the gravity feed method, so I've never observed how it works without a pump.



