I run Neptune WAVs and two MP40s on my 650P. The Ecotechs are much quieter. I get a lot of vibration and pulse/surging sounds from the WAVs if cranked up over 50% depending on the mode used. Its as if the vibration resonates in the glass. This and the cords in the water is my biggest complaint. The cords do vibrate as well on my lid to keep my fish in. Even with the cut outs for the cords on the lid. Both of my WAV's failed a couple weeks before the two year warranty expired. Roughly 1-2 weeks apart. Neptune took care of me and replaced them both.Are they silent? I've never owned a vortech but so many say that they are fairly loud. My powerhead setup will be pretty similar to yours on my new tank I think. (it's going to be a reefer 650)
As for my Ecotechs. I have never had any issues with either the dry side/Controller or wet side. I have over 10 MP units I have Wet sides that are 4+ years old. Routine cleaning and inspection helps. Not to mention don't drop the wet side magnets. I would say this is most likely the reason fine cracks develop allowing water to seep in causing the rust. It's possible there are some bad ones out there but I don't buy it until I see it happen personally. Also I suppose running them at 100% 24/7 may heat up the magnet housing cause them to fail with expansion.
Recently another R2R member stated his WAV pumps caused his EB832 to fail causing the entire power strip to shut down. I don't like the sound of this. I like that my Ecotechs are on an independent power source with the Ecotech backup batteries.