Upload & Sell: Off
The 1Ds II is, in a lot of ways, a much nicer camera to use. The build quality, autofocus, weather sealing, form factor, mirror blackout, and viewfinder trump the 5D II, sometimes by quite a bit.
But the 5D II has better image quality, and you'll lose the massively improved UI, Live View, AF adjust, small size, larger and more color-accurate LCD, quicker image review, and all the little niceties Canon rolled into four years of development.
As ever, it's a question of what you value. I picked a 5D II. I love the UI and the form factor, I regret the AF. With the 1Ds II, it'd have been the opposite.