Yeah, I've discussed similar studies before. There's lots of data to this effect. I'm pretty sure I've referenced this study too.

Foot retention does offer benefits over platforms, namely:
• It gives you more control in high-RPM / high-power situations
• It helps ensure your foot is in the proper spot for your fit
• Modern bike shoes ensure you're using a rigid sole

Foot retention offers very little benefit strictly in terms of power generation, though. As the study demonstrates (p5) amateurs and pros alike apply very little power on the upstroke, and a bicycle operates like a 2-stroke engine. Even when you show people charts and data, though, many refuse to believe it, or insist that the extremely tiny and nearly immeasurable amounts do matter somehow. C'est la guerre.