After several fashion shoots using the 5DS R, I finally encountered a garment that gave visible moiré that would likely not be present (or as severe) with the 5DS. In this case, it was a very fine, dark blue denim. The moiré is pronounced in this example, but it's only present in 3 of the 40 shots I took of the model in these clothes. It required just the right combination of fabric pattern and specific light angle to occur.
Also, the color noise reduction Lightroom cleaned it right up, using the smoothness slider. This is just one of many ways, of course. All in all, not a serious problem. Something to consider if you're deciding between 5DS and 5DS R, the moiré issue for still photography is real, but difficult to reproduce and--in my experiences so far--easy to selectively remove without having to sacrifice the sharpness of the whole image. The photos below are 1:1 crops if you click through to Flickr.
Moiré on Jeans:
Removed by putting Lightroom color noise removal smoothness to 80%:
IMAGE LINK: https://flic.kr/p/FyNFBf



