Mark,
The "distillation curve" is helpfull to look at. Chevron has some really nice info in thei publication Aviation Fuels. Check the graph on page 47.
http://www.cgabusinessdesk.com/document/aviation_tech_review.pdf
The different gasoline components have different jobs, the graph illustrates that very well.
There are distallion curves for mogas as well. One thing that you will see is that using a winter blend mogas during the summer is not the best idea. When you look at winter blend gasoline, there will be very early boiling components in that mix so cars start easier in the winter (the winter fuel will start boiling- making vapor- at a lower temperature than the summer blends). That means they are also more likely to vapor lock during high heat conditions. This is not a fuel I would want in my airplane in the summer on a hot day!! Best burn it up before summer, unless you are set up like Frank's airplane, his system would probably not even notice.
The fact that gasoline can be made of so many different components, puts a kink in the idea of "pure gas". The concept of "pure gas" might be good as a marketing term to explain there is no ethanol on board, but reality, the "pure gas" is right there on the shelf next to the pure trail mix and the pure gardening soil...