Understanding ProPhoto RGB

Most photographers work under the assumption that Adobe RGB 98 is the most suitable working space within Photoshop. Everyone also knows that the sRGB working space is smaller, and therefore less suitable for professional and fine-art printing applications. Sure, sRGB is fine for amateurs and the web, but real men use Adobe RGB – right?
Well, not really.
One of the most knowledgeable voices in the area of colour management over the last few years has been Bruce Fraser, the co-author of the current definitive work on colour management for photographers – Real World Color Management. In articles that he's written elsewhere Bruce suggests that digital photographers should consider working in the much large ProPhoto RGB colour space. (ProPhoto RGB was developed by Kodak).
Though I'm familiar with the book and many of Bruce's other writings, and I knew that ProPhoto RGB is a bigger space than Adobe RGB, somehow there wasn't a mental connect – until recently.
What happened was – I had an epip...