Gidday Joel

The reason the colour space is showing as ProPhotoRGB in the save as dialog box is because this is the colour space you have assigned when processing the RAW file in ACR.

For all sorts of reasons, use aRGB colour space and 16 bit processing for the safest and best results. This advice is based on you using an aRGB, calibrated monitor.

As I wrote above, I always use ProPhotoRGB -16, but I also understand what I am doing, and only extremely rarely do colour adjustments.

Colour and colour spaces are very complex topics. They have even determined my choice of cameras, as Olympus get the colour filter array (CFA) about as close to neutral as I have seen, and that's what I want for my photography.

ProPhotoRGB -16 images will look really ghastly on any monitor that can only display exactly an sRGB colour space. Many 'sRGB' panels are also only 6 bit, which doesn't help ...