I've used one for close to ten years. Mine is VERY loud (it could probably use some lubrication which might reduce the noise a bit) but it is bulletproof, easily serviced and the two heads result in a very accurate exchange of new and old water. I have mine mounted in my garage so the noise is not an issue. My wife would kill me if I tried to mount it in the house.
I use one and like it. It is loud but not horrible. My chiller is louder. I run it at night to avoid the noise. This is my favorite method for auto water changes and I wish someone in the industry would make an affordable dual-head option that was more consumer-friendly.