Hey guys.
Sorry to barge into your forum uninvited. CoralFarmer at Caesars turned me on to your club. I've been pondering this very issue.
For what it's worth, I popped for the EcoTech a couple weeks ago and I'm pretty happy with it. I have a 100g with a noisy overflow, so the slight noise from the external portion doesn't bother me. It definitely moves water.
There is a droning sound when the unit is running at high speeds. The alignment of the wet and dry parts is critical here to reduce noise in general. Also, the droning can be always be controlled / eliminated by turning the pump down.
I run it in Reef Crest mode and I don't hear the changing of speeds. I do sometimes notice when it's on high from the slight droning.
The light on the controller is too bright, imho, but I like how it changes color to indicate mode. It's like having a night light on by the tank, which I'm not crazy about in general.
My thoughts (crazy man talking) go towards getting a second one and running them at opposite sides of the tank in anti-sync mode. Talk about your tidal currents back and forth!