I wanted to report back on the single EcoNet EV100 I received a week or so ago. In a nutshell I love it.
It fit like a glove when replacing my existing 6x10 dumb vent. This was one of my concerns, that it wouldn’t fit right, or the mechanics would be hindered by the ductwork. It effortlessly replaced my existing unit.
It connected to ST pretty easily. As anybody knows that has connected lots of ‘things’, it sometimes takes a couple of times. In the end it was no harder to connect than any other z-wave device. Took me a couple of minutes tops.
It was recognized by smartthings as an “EcoNet Vent”. It even has it’s own icon of a little vent. 
It is basically a light switch with a dimmer. I can turn it on, turn it off, and have it go from 10-90% in 10% increments. One odd thing is that if you want to go from 30 to 40%, it goes from 30% to open all the way, then closes all the way, then goes back to 40%. In the end not a big deal, just a little odd.
It was quieter than I expected. I won’t call it silent, but my wife said she couldn’t hear it with my two little kids in the room. Once it was totally quiet, you can hear it, but its better than I expected, and much more quiet than say my Kwikset 914 lock.
A small ding is that when it opens it flashes a green LED. When it closes it flashes a red LED. It doesn’t seem to bother anybody as my vents are on the ceiling upstairs, but it would be nice to be able to have no lights as a preference.
I set it up with the “Virtual Thermostat” app which is in the Green Living section. It basically does everything I want. I have it open below 71 degrees, and it is closed above 71. This app also includes motion, which I will use when I get additional units for my guest room. Basically it stays closed unless there has been motion in the last X hours. It’s perfect to be honest.
Bottom line, I am totally satisfied. It is working exactly as I expected and wanted. Prime example is my HVAC is off all day. When I get home my HVAC kicks in and it would bring my upstairs rooms above 80 in order to get the entire downstairs to 69 degrees. I have one EcoVent in a room to test and that room now stays at 71, while all the other upstairs rooms continue on to 80+.
I am ordering 4 more asap for the rest of the rooms in my upstairs.