I haven't tuned my Avalanche - yet...
I have a K&N 63-3070 intake kit sitting in the garage. And, I have a Corsa "Sport" cat-back exhaust P/N 14914 being delivered tomorrow. My plan is to get an average MPG with my Avalanche completely stock for at least the first few thousand miles (I just rolled past 1,000 miles last week - I purchased it new on 3/6/12). Then, I want to see what kind of improvement I can get with the intake, exhaust and tune installed.
Obliviously, the mods listed above are more geared towards performance improvement (adding HP & torque), but an added benefit can be increased fuel economy when driving in a more conservative manner. But, I will still have (and definitely want) the increased HP/torque there when I want/need it.
I'm not familiar with Edge tuners. But, the Edge GM EvoHT tuner looks eerily similar to the Superchips Cortex 2950 I have that I will be using with my Avalanche. The Cortex 2950 worked very well with my Corvette. But, when I saw that there was no "fuel economy" tune available (even after updating via their web site) I called Superchips directly to ask about that. They explained that while it was a correct Superchips tuner to use with my Corvette, their products are designed more for use with full size trucks. Superchips recently released an update for the 2950 tuner that includes 2012 Avalanche's. And, it has a performance tune and a fuel economy tune. So, that is why I'm going to use the Cortex 2950 on my Avalanche.