Also I am worried about the 100ll situation, dont want to be left with a pup no one wants!
I haven't spotted anyone picking up on this fine question.
I'm guessing (as a lowly 26 hour student!) that even if 100ll were removed tomorrow and the engine couldn't be converted to run on mogas or mogas+some additive, worst case would be replace the engine (though with what?!), so the whole aircraft won't be a pup - the airframe & avionics will still work with the same physics after any withdrawal of 100ll as before it!
Any thoughts from you properly knowledgeable guys and girls?