Originally Posted by
ffsim
If one has a detailed enough understanding of how one's money is spent, one can maximize the use of both cards since MR converts 1:1 to Aeroplan as you said.
For example, I book all my travel on the Amex Gold, for 2x MR, but buy all my groceries on the TD Aeroplan, for 1.5x AP.
I keep a little sticker on the front of each card to remind me which one to use for which.