Desperado - You just matched my sentiments of the last few weeks. I laugh everytime I read people post on the Mazda Forum how awesome someones car is if they have the AEM Standalone. People will switch from Haltechs, SMT6's, etc, because they believe that the AEM automatically gives them more power. "OMG!! It's teh ROX!!!1!" (and yes, the AEM may have additional features, I'm strictly talking about people using it for fuel/timing)
Megasquirt is just another tool used to tune, and how the engine runs is the result of how good/bad the enduser is. Not how pretty the software looks. My buddy just built a Megasquirt for his turbo Integra so I'll be watching to see how it runs.