Thanks Dan. I believe even ListTransformations isn't available in the pre-3.0 version of the ArcPy library. It just seemed surprising to me that prior to 3.0, there was no option to read/write Map Transformation information, when that has been available on the DataFrame class in ArcMap for a long time.
Regarding updateTransformations, does this actually set a transformation on the Map, or just limit the dropdown list somehow that you'd still need to pick from manually, do you know? Also, will Pro automatically use the first transformation available in the list if none is explicitly specified, or simply not use one at all if a transformation is required?