He rode it in the post-season test, and was immediately despondent after the first lap, and didn't get within 2 seconds of Stoner in that test.I agree with you that it's unlikely anyone else could have won the title on the GP7. Loris Capirossi who rode so well with the 990 GP6, could not replicate his 2006 season at all. He did take the win in the wet at Motegi, but he looked thoroughly lost most of the season on that bike and only pulled together a couple of good rides.
Hopkins is an interesting one. I think he would have made a better number 2 to Stoner than Capirossi, but how much better I can't really guess at. Very talented rider who I would have liked to have seen get a chance on a better bike. I always felt he came into GP at the absolute wrong time and for the wrong team...and then the Kawasaki move just killed him.
The one hypothetical that's fun to mull about is what if somehow Ducati could have fielded their 2008 lineup in 2007? I would have liked to have seen Melandri on the GP7 to see if he would have handled that bike any better than he did the GP8.
Marco was very equipment dependent, I don't think he was much good on a Yamaha either.