Digital BW, The Print

Excellent info, and thanks for posting it.  Just one question.  One 
of your steps is 

"Open Photoshop and your image then assign the profile "Grey Gamma 
2.2" to the image."

I'm using a Mac, so I assume I'd do Gamma 1.8 here.  The more 
important question is, why does it make a difference what Grey 
profile you assign (or whether you leave the image in RGB mode, as 
some of my images as RGBs)?  I mean, I can easily change the profile, 
but I'm just curious as to why or if it makes a difference with the 
RIP.