ECU Choice..

I'm looking to convert to multipoint, but I'm torn between more power and more gas mileage. I drive pizzas all day long so my engine runs constantely so I would like to get awesome gas and make even more, but more power might be nice. I hear the programs in the PM6(Si) and PM8(HF) ECU's are extremely similar. My engine is a somewhat newer JDM D15B 16V non-vtec running on my DPFI. I'm wondering what you guys would think if I were to convert to mulitpoint and use the HF ECU on my 16V engine...would it run lean, would I get more gas mileage or more power since the HF is restricted in power only by the 8V configuration...interesting? What do you guys think.

I'm not looking to replace the head.