Well there are two reasons I was surprised they didn't use the 1080, one was that it is surprisingly hard on a GPU to do the sort of lag free drawing/manipulation. When I'm turning a 3D part around in "quality" render mode in TurboCAD and modifying it on the fly it works out the GPU fairly well. Unlike games its pretty much forced to recompute lighting fairly often.

The other was that they have already crossed over the "luxury" threshold from "just another PC" to "special hotness" sort of territory. So unless Nvidia is giving them a smoking deal on "old" GPU's it seems that from a marketing perspective you would want to check off all the boxes. Its reported that it would use less power and generate less heat, and Nvidia says it is 20% faster. That seems like it would be a "no brainer". But I clearly don't know.

That is why it surprised me when I read the high end Studio only had the GTX980 in it.