I'm an electronic engineer in Auckland NZ, and the MegaSquirt looks quite well designed. It has been around for some time, and a lot of improvements have been made. The hard part is to fine tune it for your car to achieve optimum performance, but that rather means tuning it to your sensors. Air flow meters are extremely accurate, but no 2 sensors are the same. I've got an industrial sensor here that is within 0.5% repeatable, but the linearity error is 3%. Once characterised, it is spot on.

I can't remember now, but if MegaSquirt use a look-up table for linearising the AMM, then it will be fine for performance tuning. But I think it uses formulas, which is not the best for performance tuning. Mapping, however, is not so simple, which means that MegaSquirt is ideal for the home mechanic. It will definately improve performance and require much less maintenance than a carb or your standard FI of the 70s or early 80s.

Would be great to hear about your experiance, and I'm planning to probably add a MegaSquirt to my 144 in the near future. Stromberg carbs are fine, but I'm an electronics man...