Digital BW, The Print

It is true that the direct conversion to greyscale from  RGB  in  
Photoshop  changes to the red channel.  You can check this easily by:  
converting an image to greyscale in PS by: Image>mode>grayscale.  Go  
to Edit and select 'change profile to rgb'.  Go back to Mode>Channel  
mixer and you will see that the red channel is at 100%  Don't know  
about scanners.

Lincoln