QTR-Quadtone RIP

sort of a basic question from a very newcomer, given a printer like
the epson 2400, which seems to have a good preformance for black and
white printing, is there any aspect of a print that will suffer some
sort of hindering when printed as an rgb document previously toned to
taste from the original grayscale?

I'm assuming that a printer like the 2400 uses only 3 cartridges
(black, light black and light-light black) for printing a grayscale
document, if the document is toned (by toning I mean sepia or similar)
then the document becomes rgb and, therefore, the printer should use
additional color cartridges.
 
thanks,
 Rodrigo