Digital BW, The Print

That depends on how you're printing your B&W images. If you're using
the RGB driver with regular printer/paper profiles, then you'll notice
a slight difference between Perceptual and Relative Colorimetric in
the tone response, usu. with a bit more shadow detail in the former.

If you're printing with the ABW mode then you shouldn't be using the
standard VFA paper profile because that profile is designed for color
work in the RGB driver only. You should instead be following a
workflow similar to this:

http://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html#abw_no_gray_curve

The exception is if you've had a special profile made for use with the
ABW driver.

Eric