Acheiving a "subjectively exact" exposure between two different bodies, apparingly having fundamentally different tonal curves is not easy (and honnestly - I didn't spend any time on it either).

But nevertheless - study this roof tile, shot on a terribly rainy and grey day in very low contrast light. The 1Ds highlights do IMHO lack some color detail. I somewhat like this charaterisic in some scenes, but in this one I wouldn't mind some less "whiteness" in the highlights. Very subjectively...