Rev-N-Nator vs. FBO HRR688 ignitions

I had a Rev-N-Nator for awhile but sold it. The instructions state to NOT use vacuum advance so I plugged it.
In one tank of gas going to Southern CA, I got 10.6 mpg while driving at approx 65 mph. After the car show, I put in a MP Chrome box and ran vacuum advance and at the same 65 mph average, I got 12.8 mpg.
The only drawback to the Mopar Performance ECU was the lack of a rev limiter. The power was about the same.
Mileage isn't a huge factor for me with these cars but if two products give equal performance but noticeable gas mileage differences, I'm going with the better mpgs just out of common sense.