RE: CIBC Aerogold Infinite card interruption on reward ticket info -- says you need to submit---
"Your original booking invoice/itinerary from your travel agent showing
all portions of your pre-paid trip cost and confirming that 75% of your
trip cost was paid using your card or if 75% of your trip cost was paid
through the redemption of points from the card travel reward program"
Amex gold gives you double points for travel so it looks like if you are only booking an Aeroplan redemption then you are best to go with your CIBC card (Amex doesn't give double points for Aeroplan - at least I have had no luck asking for it)