Recommendations on Colours Space for Printing
Are your images in ProPhoto RGB? At this time, there is no printer or monitors capable of printing or displaying the full range of colours in the ProPhoto RGB colour space and your image may not print as you expect. Photohop recommends converting your ProPhoto images to Adobe RGB, which our printers are more than capable of printing. You are welcome to submit images in ProPhoto RGB, but we cannot guarantee that you will get the results you were expecting.
Though there are many who will argue this point, from Photohop's experience, images in the ProPhoto RGB color space can produce some unexpected results when printed, and sometimes those results can be very drastic. If you are sending Photohop images for printing, we advise you convert those files to Adobe RGB. By doing so, depending on your monitor's capability, you will have a better representation of how they will print.
Keeping working files in ProPhoto RGB is a good practice because you never know what the future will hold for printers and monitors (which currently can't show the full-colour range of ProPhoto). Until the time comes when printers and monitors can reproduce ProPhoto, submitting files in either Adobe RGB or sRGB is highly recommended.