I faced this exact dilemma just a few months ago. I was all set with Explorer EFI components, ECM, harnesses, and I even had an appointment with EFI guy to rework the harness and Flash the computer.
Unfortunately, due to emissions controls laws, EFI guy was not able to delete EGR or other components so I would have had to run at bare minimum with a check engine light all the time.
I opted to go with Edelbrock proflo 4 for several reasons. First and most importantly, you are not faced with legal limitations regarding the programming. Second, the computer is not part of the throttle body, which seems to be causing all the Holly guys grief. Thirdly, it is Port EFI and not throttle body EFI. Lastly, all of the Explorer or Mustang computers from Ford donor vehicles are getting long in the tooth and it may be hard to replace components at some point in time.
I watched the videos on Nashville early Bronco:
which were extremely helpful in making the decision.
The install went great, it was fairly easy and it looks clean. I'm actually planning my initial startup since 2006 later today or possibly tomorrow! I'll let you know how it goes.
THX,
JB