Dave,
I noticed on the front of a JEGS book that MSD has a super slick version of their system called "MSD Atomic EFI LS" for the Chevy LS motors. The electronics are all incorporated into the fuel rails, so wiring is minimal, and no separate ECU to hang with it's elephant trunk bundle of wires to the engine. Very clean, but not sure how much you can do in the tune it yourself arena. Seems to me that MSD does their self learn, but then has optional screens where you can go beyond that if you want. Might be worth a look....