The Duc is currently the fastest. Just look at the top speeds recorded so far. They held most the the top speed records last year too. What they've done with the 800 is truly impressive. In world superbike Ducatis lost it's stranglehold. Toseland on the Honda currently leads with Haga on the R1 coming up fast.
Stoner is an amazing talent. According to Rossi Bridgestone is the better tire this year and he thinks that tires are more important than a power advantage. Capirossi is riding the exact same bike as Stoner with nowhere near the results that Stoner has been racking up.
The Yamaha suits Rossi just fine, he probably wouldn't have a 21 point deficient if he were running stones.
What if is a waste of time. Stoner looks like the real deal to me if theres a pretender it's last years champ Nicky Hayden. Not even a podium this year.

Another vote for the Ninja 250 for commuter bike. 55-60 mpg and a ton of fun, almost as much fun as the R1.