speaking from personal experiance, edge is alright for a little extra power. it made no difference to my mpg no matter how i drove it. sure your goona get better milage when you take it easy on the pedal but you would get the same increase if it were stock. i think there a better products out there. i don't think it's a full on waste of money but they don't seem to be much cheaper than other chips that are better quality.
i guess it's a little like buying a chevy. it does what it was intended to do but not very well and there are a few better options.