I'll be posting a mini-review of them soon with pics.
I bought a pair of the EFB1212LE versions. At full speed, their volume is about equal to a Panaflo 120mm L1A. I run them typically at 800-900 rpm, where the are extremely quiet. They can go lower but the rpm sensors drop off after 650 rpm or so. With regard to motor noise, there is a very soft ticking at low speeds. You have to put your ear near the fan to hear it. At higher speeds there is more motor noise and air noise, but not intrusive at all.