I've had mine since September. Once the hemi broke in, I'm seeing about 16-18 mpg with mixed driving. I saw at least a 1mpg change after switching to full synthetic as well. I always run 89.
My wife has a 2016 BMW and it's start/stop is HORRIBLE. I mean so bad you have to turn it off and never use it because it feels like the car struggles to turn over. However, the etorque is so seamless that with the radio or AC on it is easy to forget it's working. Plus, if you are sitting for an extended period of time, it kicks back on to avoid killing the battery since the truck is off but still running everything.
Aside from the many other positives for the etorque system, the added 130 foot pounds of torque for those short spurts is really nice.
The only thing that worries me is the backorder on the boxes because of the demand/new technology so if it goes out you might be screwed for a while. I've got an extended warranty, but I would think replacing it would be at least $2000 to replace it (parts/labor).