It seems like a very nice system. It is totally DIY, firmware and PC
software are free and open. It does not control the ignition, but there is a more complicated version which can. The older, more complex EFI332 system can also do fully sequential injection even for a V8.
On the C20LET, you might be able to disconnect the injectors from the STD ecu, run the two systems in parallel, so that the motronic thinks it controls Amal valve and injection, but doesn't.
The megasquirt appears to have an onboard manifold pressure sensor which can handle upto 2.5 bar. The built up system with std firmware is supposed to handel upto 21 PSI (1.45bar) on turbo and supercharged engines. Megasquirt monitors lambda and other sensors, to get the correct fuelling at these high boosts.
The judder that you get from a std motronic when there is too much boost/weak mixture I assume is the motronic ecu backing off ignition when it sees it can't fuel properly based on lambda readings. If this is the case, you could still have useful ignition protection, plus rev limit protection from the motronic, while megasquirt fuels at upto 21psi boost.
Megasquirt should also be able to control the amal programatically. Megasquirt has 2 injector banks, so is not fully sequential on a 4 cyl without modification. If the injectors are wacked open most of the time this should have little or no effect on max power.
The potential advantage of this over any other system is price and flexibility. When you do that little extra mod on a Sunday, you can setup the car yourself on the spot, there and then. No expensive mapping software.
As you bulk purchase a kit of parts with other megasquirts, basic costs are 110 dollars for the ecu.
I`ve had mine running and first impressions are good, but i`m waiting on a throttle spindle from eurocarb before i start mapping properly.seems very easy to use. once i`ve got my spindle sorted out i`ll let you know how it goes. i`ve converted an old set of dell`orto dhla40s into throttle bodies.