The 100S doesn't offer neutral b&w prints.
This was an unpleasant surprise for me personally as I shoot exclusively B&W film.
I used to own a Pixma 9000 MK1 which although only had one black ink cartridge, would if set up correctly print true neutral monochrome images even though it could take twenty minutes for the one cartridge to throw out an A3 sized print.
A number of years later, took the plunge on the 100s only to be horrified that even in so called monochrome setting, taints are still visible.
Communication with Canon to rectify the problem ended with an explanation that the 100s does not offer the same neutral b&w printing that the 9000 did even though the more modern printer houses several black / grey cartridges.
As it is, after a lot of test prints, I've got the results as near to a true monochrome that I reckon I will ever get with this printer.
For me I can live with it although I will be very cautious with any further purchases of printers regardless of make.