In the Photoshop Print-Preview dialog for CS4/5/6, there is a check-box for:
 Gamut Warning
along with "Match Print Colors" and "Show Paper White"
My understanding is that the "Gamut Warning" provides a very simplified "soft proofing" capability just before printing, to show what colors are outside the printer printer profile being used when "Photoshop Manages Colors".
However ... in the Scott Kelby book, " Adobe Photoshop CS6 Book for Digital Photographers" on page 372, there is the statement:
"TIP: The Gamut Warning Isn't for Us
The Gamut Warning checkbox (beneath the preview area) is not designed for use when printing to a color inkjet (like we are here) or any other RGB printer. It warns you if colors are outside the printable range for a CMYK printing press, so unless you are outputting to a printing press, you can leave this turned off."
Is the above statement correct?
If not, is my understanding (above the quote) more or less correct? Or flawed?