Reply to "Adding Speed Density to IR EFI?"

"On radical engines (those with cam duration over 240 degrees at 0.050 or less than 10 inches of idle vacuum), even user-programmable Speed Density systems have difficulty due to an erratic or insufficient manifold vacuum signal."

I guess the real answer is that they haven't made a good system for IR yet. MAF would require a single intake of some type, speed density requires vacuum sensing, which means you need a plenum before the runners, and N-whatever isn't any better than mechanical hillborns. I got a feeling all of them will work just fine, but one or the other may stumble or cough now and then.
You can't really go wrong cause you can always change it later, plus you get the fun of playing with it. So just buy the most programmable thing you can and read the instruction manual and play.