'How many megapixels do you need?' always reminds me of my children: 'Dad, I need an icecream!' The point being that most of us most of the time dont need huge pixel counts for our usual outputs. 'Want' though is another matter
I would love to upgrade to the 1DsIII, but I really dont need the extra resolution, even though the newer processing engine, better high ISO performance and built-in sensor cleaning would be nice. (I can always find excuses for more kit, if only the money were as easy!)