thruthefence - glad it worked out for you.
As someone who has an entirely homebuilt EFI/Mapped ignition engine management system, based on Megasquirt and junkyard hardware, built into a 60's Triumph, I think those who rubbish aftermarket ECUs in general and Megasquirt in particular are missing the point.
Sure, modern (say mid nineties on) engine management is much more sophisticated and better mapped. But, if you have a situation where your car either never had fuel injection, had rudimentary fuel injection from a bygone age, or has modifications outside the ability of the stock ECU to allow for, then you have a problem. These wonderful modern ECUs are not easy to modify or to apply outside their intended application. Aftermarket therefore fills this niche.
I can only speak for Megasquirt (MS), but I found it to be very cost effective and reasonably easy to use, even with no prior EFI/management experience. Power, torque, fuel efficiency and driveability, yes driveabilty, are all significantly improved over the standard carb/points setup. With a wideband oxygen sensor I can set target tables to control AFR over the working range. The open format means I can use software created by a number of clever people (for free!) to help me tune and tweak the maps and get the best out of the car.
Can it achieve todays emissions legislation for new cars? - I doubt it, but that is not the point of it. However, I would be very surprised if a properly set up MS installation does not drive every bit as well as a modern factory build.
Sure, plenty of people have problems with their MS installs. Plenty of people have problems with the other other aftermarket systems too (not to mention OEM!), but with MS you see alot about it on the web because that is where you go for help. The low cost of MS also means it falls into the hands of backyard tinkerers who are punching way above their weight....
Just a case of horses for courses really.
Nick