Sorry to resurrect a dead thread, but I was working on my tank just now, and thinking about buying a hydor to put in my sump to help blow around the detritus per the "tips for keeping acros" sticky, so i was researching and found this thread.
I was thinking about the hydor I have in my DT. It is over 10 years old, it is the most powerful first generation hydor, and it works great still. I will probably replace it soon, but man, ten years and three reef tanks. pretty impressive if you ask me.
I can only relay my experience. 3 years and 2 cracked circulators. This could have injured me and my livestock (which I am convinced it did). I'll never buy again.