Aaron Nace has released a really good video on this subject:
Color Spaces Explained! sRGB, Adobe RGB (1998), ProPhoto RGB. He also walks you through applying the proper settings for ACR/Photoshop and Lightroom to ensure you stay in the proper color space while editing (some of those settings are tricky!)
I seem to recall having had some issue when using ProPhoto in the past but I can't remember now what it was. More importantly, I learned a couple things from this video and they ultimately led me to reconsider my choice of color-space (aRGB). Aaron has me convinced and I'm now using ProPhoto again... I'll see where it gets me.
...