I have the Edge Juice w/Attitude. I thought you couldn't turn it off either. The Edge EZ can not be set to stock, except taking it off. Then one day with the box on Level 1, I pushed the down arrow and there was Level 0(Stock). So you can set the box to stock and still have the monitoring available.
I wish that I could tell you what Level 1(Mileage) did for a full tank. Just cant seem to stay on Level 1 that long. I ran on Level 1 for a while before I realized that the fueling option for that level was set to 3 by default. (1=lowest fueling/5=highest fueling). I set Level 1, 2 and 3 to lowest fueling. I have been trying to stay on Level 1 at that setting to see if I really gain mpg. I think that with that setting combination that I am seeing better mpg. I will have to do it for a full tank to be sure though.
When I decide to get radical with BOMBs, I will either get the Juice upgraded to HOT version or switch to the TST box. I am happy with the Juice w/Attitude so far, even though I have an issue with the Transmission Lock Up monitoring. Edge is sending me a new Juice/Attitude to solve the problem.