I ran Jebao 150 for 3 years with no issues - except they get dirty and slow down... cleaned every 2 months. I cleaned it thoroughly and packed it up, and I'm fairly certain it will still run if I need it to later.
A few months ago, I switched to Icecap 2k on one end and 4k on the other with the Hydros engine to get a natural, diverse wave. The tank has never been better.
All gyres I've had make a light whirring noise. If it's noisy there's something wrong, either dirty or something's stuck in it.