One serious danger that has not been mentioned, and I have experienced it, and seen it happening with glider tugs, is that due to the much lower boiling point of mogas, if you land having been using mogas, and sit on the ground for about 15 mins, the carb body heat soaks from the engine, and then if you start up and taxi for take-off, you can get a rich cut due to the petrol boiling in the carb, and the only way out is through the main jet into the manifold. When flying the high fuel flow keeps the carb cool. I use mogas in my Jodel, but keep avgas in the front tank for take of and landing. The main reason most people have for mogas is the difficulty in getting avgas without a long flight or a high landing fee.