I briefly wanted to say that in the 41st Parliament, Bill C-23, for the first time, broke the barrier against Sunday voting. The previous Conservative government had put in the legislation that advance polling would be mandatory on Sundays. That's the current state of the law, as far as I know it.
What Nathan's amendment would do would be to provide a voting day quite close to election day, but this would not be breaking a precedent or a taboo on Sunday voting. That was done by the previous government.