There's an article comparing CIBC's Aerogold and the new Royal Bank Avion cards in the Globe and Mail this morning:
The catch with Avion is that you have to stay over Saturday night to use your points, and you have to book two weeks in advance for North American flights and three weeks in advance for global flights.
Avion and Aerogold also differ somewhat in the number of points you'll need for a free flight. Short-haul flights in Canada would cost 15,000 points with both Avion and Aerogold, but a New York-Toronto flight would run you 20,000 Avion points and 15,000 miles on an Aerogold.
As well, there's a price cap on tickets booked through Avion points. For example, your points would pay no more than $400 toward a Toronto-New York flight. Royal says the caps are high enough to cover the vast majority of flights, but this is still something to be aware of if you're expecting to fly for free.