1Ds-3 for event photography

Hoping to hear from those using a 1DS-3 for live event photography. 99% of the work I do is bands on stage for newspaper and web work. The environment is low light, changing colors. I currently use a 1D-3 and it is great for this purpose. The fast frame rate is not as important to me as its ability to focus in low light. I now have a chance to get a 1DS-3 as a 2nd body and am wondering if it is up to the task. The 1600 ISO on the current camera works for my purpose as well as it's ability to focus in low light. Will the "S" be as good? I am using a 70-200 IS-2 2.8, 24-70 2.8, 135L 2.0 as well as a 17-40L 4.0 which I will probably sell if I get the "S". You input is greatly appreciated.