Finally got my car back the other week after getting the heater probs fixed, along with the upgraded ECU.
I'd say it makes a difference. The car feels much more lively, my immediate reaction was "f'*in hell" once I got some clear road. Although this could just be in my head after driving the boring rx8 for 4 weeks

. The annoying lag before the psychotic cam changeover kicks in has gone. Instead, its much more smoother onto the cam changeover a bit earlier. Car is much more fun to drive.
Also, I am getting about an extra 20-30 miles out of a full tank of fuel. My fuel light usually comes on after I have covered about 250-260 miles. But since the ECU upgrade it comes on at 280ish. Maybe due to fact I'm spending more time in 4th gear vs 3rd gear (not sure). Could prob squeeze more out if I turned the ac off and drove around like a grandpa
I would definitely recommend getting the upgrade. Get in touch with Craig at MMC. He can offer good prices.
03 Nissan Micra 1.0 (Silver) ... 0-60 in 18 seconds !!!
04 Mazda RX-8 (Silver)
58 Lotus Elise R (Starlight Black)
"Lotus Elise - Designed by gods, built by monkeys"