The price mistake is gone. Last september they offered the 70-200 IS at the wrong price, and *thousands* of people called and ordered, as word got out on dpreview. They quickly fixed the error but were good enough to fill the orders they'd received, even tho folks had to wait for months to get the lens.
Panga, I love my 1DS. It's not the fastest camera in the world, but oh those pictures. Look, I'm doing more and more bird photographry, the 500 almost always has the 1.4x on it, and although the picture quality is good, without the 1.4x it's outstanding.
How heavy is your 600? The Canon IS is 11.5 pounds. My 500 is 8.5 pounds.
My fav Canon lenses:
300 f/4 IS: Wow, I love this lens! Super light, IS, and oh so sharp. 50mm f/1.4: yup 28-135 IS: yes, consumer lens, but I've shot professional product and model shots with it just fine 135 f/2: wow 500 f/4 IS: ooooh.