Is shaw 20gb up/down? When I called them up a long ago, they told me that there was only 1gb up and 5gb down. They don't monitor it like freaks, if you go over, it is fine as long as it isn't too excessive. Anything over 20gb will be noticed though. Maybe they changed it since?
Telus was the same limits too. I guess that both companies must have swtched since then.
You may want to call them though to make sure. If it is true, then Telus would obviously be the better deal since you can transfer more data for roughly the same monthly price.