Sooner or later an idea is going to stick and right now Sean and I have been talking about going to a cheap and common arduino compatible main board to talk to the tunner, run the model and provide the analog inputs then couple it to a getting pretty common and cheap fpga board to handle the time critical stuff.
Its the time critical stuff that rules out most chips. the o5e project used the mpc5xxx chips but the tools are closed and expensive so not diy friendly. FPGA chips have been used in ecus (cosworth F1 stuff) but where crazy expensive and tools more expensive, but now chips are $5, lots of dev boards
in the $15-$50 range and tools that are functional and free.
I think this is take 3, and 3's a charm right?