QTR-Quadtone RIP

Tom Moore pointed out something interesting in an earlier post: when
converting to Roy Harrington's provided gray-lab.icc profile to use as
a working space, the shadow end of the scale blocks up (using the B&W
test image provided at the Northlight Images website). In the readme
file provided in the profile folder, it says using this as the working
space "spaces the grayscale values linearly with respect Lab or
Luminosity". It is then suggested to convert to either Gray Matte
Paper or Gray Photo Paper when printing. This conversion also blocks
up the deep shadows.

Since Roy is the expert and source of knowledge when doing B&W
printing, I must not understand something - or many things :)  It
seems that there is no value in using spaces that block up shadow
detail in an image. So why are these icc profiles provided in the QTR
installation? What is the recomended working space for adjusting
images in Photoshop prior to making prints using QTR?

I am using a Windows XP computer and an Epson 2200 with the regular UC
inks. So far I have been printing on Epson Enhanced Matte paper and
Ilford Smooth Pearl.

Thanks for any observations,

Ken