I see roughly the same numbers with the Hypertech. I run the 87 tune and have run 87 oct and 89 oct and didn't see any noticeable differences in mileage. I do however notice a little pinging when running 87 oct. Straight highway runs get me 17.5 - 18.1 mpg, running around town, I'm lucky to get low 11's with some warm up time. I've never run the 91 tune, basically because I'm too cheap to run premium, really outta try that one day. Keep us posted, really want to see if the Edge and Hypertech are just about even.
And yes, I already have a CAI installed, don't know how much that factors into my mileage, maybe 1 mpg? Throw yours on, I'm betting you'll like it!