I really don't know, Dr. Croubie.
The only reason I opted for the 1Ds over a cheaper 5D was for the servo. All the current single digit bodies have good servo performance, so I'm expecting the 6D will too. Assuming the sensor is also on par with current releases, it looks to be an upgrade from not just the 1Ds mk2, but the 5Dmk2 to me.
Better IQ, and adds usable super high ISO (compared to 1Ds mk2 and 5Dmk2)
Better servo over the 5Dmk2, unknown vs. the 1Ds mk2. (It *can't* be worse than than the 5Dmk2, based on what everyone says about it.)
Other extras over the 1Ds mk2 are a better screen, live view, movies, 20-something percent more pixels, a self cleaning sensor, and better controls (aside from the lack of portrait orientation controls).
I'm ignoring the GPS and Wifi. Don't these seems like decent enough improvements to reconsider my purchase?