An interesting discussion. Thank you.
It sparked my interest in printing in monochrome on my Canon ipf6300. Almost all my printing is done from Lightroom, and I've never been happy with the results when selecting monochrome in the printer dialogue. The print is always initially much too dark and contrasty. Mostly for convenience I've printed my B&W images in rgb, but I have to be careful to avoid colour casts, particularly in the shadows.
It occurred to me that converting the file to greyscale before printing may solve this issue.
I went a step further and downloaded QTR. I printed off QTR's 21-step grey wedges and measured them with a Datacolour Spyder and dropped the results into the QTR-Create-ICC droplet for linearisation.
Then converted the photograph to greyscale and then QTR's gray_lab using Photoshop's "convert to profile" ("assign profile" came out nasty).
There is probably an unnecessary step in here somewhere, but the upshot is a print using Canon's monochrome setting that matches what I see on screen, with the shadows opened nicely and a more subtle tonal range. Turning on softproof shows a quite minimal change, apart from a shift of the histogram a little to the right.
This is great news.
David