low light clubs , theater performances which body would have better iso performance at iso1600 & iso3200, the af of the 1ds3 will be an advantage over the 5d2 during the low light dance performances. But then the question is of price .. So Is the iso 1600 of both the cameras comparable ?
Must I add.. I am in a decision mode, the brandnew gripped 5d2 will cost something around 2800USD , wheras I can probably get my hands on an used 1ds3 for around 3500USD, I think the difference is price is easily worth the great AF & great body.

