I have had my Edge EZ on for about 9 months now, and have probably put 15,000 miles on it during that time, a lot of it pulling my travel trailer. I have had no problems with it, although it stays in #1 (lowest setting) all of the time. I bought it primarily for a little extra power when towing. Installation takes about 5 minutes and the same to take it off if going to a dealer. I don't know if I have ever read on any forum of anyone having any trouble with the Edge EZ. I wouldn't hesitate for a minute to buy another one. If you plan on towing, I would strongly recommend a pyrometer (EGT gauge), as exhaust temps past 1300 degrees are possible if you aren't carefull. I can't vouch for any mileage increases, as I don't have a DIS, and I bought my truck to pull with regardless of mileage.
2005 Chevy 2500HD, CC, SB, 4X4, Duramax, ARE Topper, 60 gallon RDS toolbox/tank combo, Kennedy Headlight Booster, Isspro pyrometer and boost gauges, EGR Blocker, PCV Kit, Bilsteins, 265 Michelin MS-2, TTS Exhaust, pulling 35' Jayco travel trailer.