I have tried all of Yeti and Nick's 808 tunes, and have been running the Yeti Mild Tune (v1.02) for around two months. I haven't noticed much of an increase in mpg (if any), but I do notice a LOT more exhaust when I accelerate, especially from a dead stop; it gets me lots of nasty looks from other drivers, especially in Boulder.
I am going to switch back to the ECR-FCV delete stock tune for a while and track my mileage more carefully to see how much difference there actually is.
When I started running the mild tune, I took a trip towing the Airstream, and there were definitely issues with TC Shudder (which I anticipated, but wanted to experience first hand to see how bad it actually was). The shift points were also not so good for towing, especially in conjunction with using cruise control, so I switched back to ECR-FCV delete stock for the duration of the trip. I can't wait for the day I get a Suncoast TC and don't have to worry any more about destroying my torque converter by supplying the Jeep with "ultimate torque."