There's actually less ethanol in the higher quality fuels as well, at least in Shell Gasoline here. I always use the premium shell gasoline, I find the throttle response is snappier (Seriously, I got cheap gas from 7-11 and it bogs quite a bit more) and pulls a bit harder. HOWEVER, the one time I put cheap gas in at a different pump (ran out and had to go to the nearest station), It was slower to accelerate, but for some reason my engine was willing to rev much, much higher, I gained a solid 5kph on my top speed and was almost able to keep up with cars on a 70kph road.
Dave has a pretty good chart, I dont know how accurate it is and I dont think it's 100% set in stone (you can prevent detonation by retarding cam timing in 4-strokes), but Ferrari's commonly run 11:1 or higher compression and yes, alot of people use race fuels with them. Our engines, if I remember correctly, run about 6:1 compression out of the box. This, of course, doesn't mean pressure is x psi, because at different altitudes, humidity and temperatures, the air pressure can vary greatly. Then your port timings, carb size, reeds or other intake mods and any sort of forced induction will also affect your pressure. But as a general guideline, dave's chart is a good starting point.
