Are there any targets made specifically for printing BW images? Will they be better for BW in comparison to general targets (for example, your 480 patch target)?
The standard 480 patch target for Colormunki (and for the i1Pro2) is already optimized for BW (128 grey steps) and also emphasizes the neutral axis (-N0.75 setting). This is most noticeable with printers having NO grey inks, but it can still improve BW-printing on printers with grey inks (K3 printers, ET-8550, Canon Pr-10/100/1000) using the standard color printing mode.