I just joined today. Here is my thought. It all depends on the dealer. I had a tuner in my last truck and now my new truck has one to. I am pretty sure it leaves foot prints even if you disconnect the battery to try to clear them. I had a Hypertech first and noticed a 9352 code if I remember it right. I seen it through the test function on the dash gauges. It wasn't there before I tuned it. I sold that tuner and got an Edge It also left a code in there two. It was a different code number, I would have to go and look to see the number. I never had any of these codes before the tuners. I tried to clear them by disconnecting the battery for as much as 6 hours. Codes are still there. The radio never lost any preset stations either. No power for 6 hours, I would had at least thought the radio would need reprogrammed, well the clock did but that was it. Those numbers have some kind of indication that the cpu has been flashed.
If your dealer is going to give you a hard time about it don't get one. Mine doesn't mind and has never given me a warranty problem about it. My opinion on the Edge is it's worth the money to get. I like it. But I wouldn't rate it the best, not yet anyways. I plan to get the SCT LIVEWIRE as soon as it's available and have it tuned by Troy Performance. I am pretty sure it will blow the Edge out the window.