A couple of links that may set your mind at ease re MOGAS:
(1)
FAA position letter;
(2)
Transport Canada bulletin.
If you do decide to go the MOGAS route, ensure that the manufacturer has approved its use, or purchase the appropriate STC (if no STC is available, personally I wouldn't even consider playing 'Mr. Test Pilot').
I hope that this helps.
MLS-12D
P.S. For what it may be worth, my gliding club has now been using MOGAS in our Citabria for one full season, without any problems (we do not fly in the winter, obviously, and that avoids potential vapour lock problems with "winter-blend" automobile gasoline).
P.P.S. While MOGAS in aviation is controversial, one thing that can be stated categorically is that most older light aircraft use piston engines that were never designed for 100LL avgas; so either way, you're using the 'wrong' fuel, with attendant potential problems.
When the giant oil companies phase out 100LL (which they apparently plan to do within the next decade), we'll all probably be using MOGAS by default.