Imola is an incredible track, but it lacks the necessary runoff in certain areas, and it also has a few unsafe aspects, like the final chicane. The 500s had around 180hp and weight 130kg. The current 1000s make 250+ and weight 157kg. They also have superior tires and ride height to help them put more power to the pavement.
The FIM races superbikes at Imola. They are probably 2-3 second slower per lap than a GP bike, but I guess that's just enough to make it reasonable safe, though it still seems a bit overkill to me. I don't see GP bikes returning to Imola, unless they take Jerry's advice and MotoGP becomes 600cc bikes that weight about 15-20kg less.
