I have the Shimano convertible (clipless/platform) with MTB shoes and do feel they are more efficient than the old tennies/platforms I used to ride on. However, that's probably more because the tennies were so flexible, as well as the platforms being rather slick so my shoe slid around on them some, especially when wet. But my gf's new Novarro has these big platforms with good grips and I suspect they would be great with a shoe that has a rather stiff sole. I'll stick with what I have for now but wouldn't be opposed to trying that out some day. When it comes to platforms, I'd guess that bigger is probably better, to spread the pressure around.