Well.... I have a sample of the 3MM TOC 53cc that I've installed and now run in my SD models 30% Extra 260. So far, it seems to be a pretty good example of a properly-setup engine design. Haven't flown it yet, but will report when I have....
Since it's actually in my hands, I used it's weights to update my Gas Engine Weights information, posted here >
http://www.rcaerobats.net/GAS_ENGINE...ENGINE_WTS.htm
Seems to be a good weight for a 3 bearing engine.