Which is $2k better spent? The 1DsMkII (used obviously) or a new or used 5DMkII?

Okay... I like having video but don't NEED it... IQ and focusing are paramount. The 5DMkII has a larger and better quality screen (I like that) but the 1DsMkII has better focusing, weather-resistance, integrated grip, frame rate (not by much) and lower MP, which I see as a plus as I don't need 21MP.

What about things like ISO performance and such? Can anyone chime in?

I have a guy locally selling a 1DsMkII for $2k. I know that I can get a used, and possibly a new 5DMkII for the same price. I'm leaning toward the 5D, but am I forgetting anything? OR.... an original 5D for half the price and put the other $1k into the 100mm f/2.8 L IS USM or a rainy day....