On the Canon 6400 I print out of Lightroom with the colour mode in the printer driver set to monochrome, QTR colour space, and an icc profile created by using a SpyderPrint 3 on QTR's 21-step grey wedges and the results dropped into the QTR-Create-ICC droplet which will also linearise the output nicely.
One issue I have with printing B&W with the mode on the printer set to "colour" is that there is often colour contamination in the print, particularly in shadow detail. It's sometimes not noticeable until the lighting is changed and by then it's too late.
The monochrome setting on a Canon printer still uses some colour inks, but not enough to be an issue, IMO.
The other advantage of printing this way is that the QTR colour space gives me a perfect screen to print match on the papers I use, without the need to softproof. I will warm or cool the print by selecting different papers.
I intend writing up the process in detail, but
Keith Cooper has some useful articles.
David