Did YEG to YYC to LAX last week and had to retrieve bags at the US customs area. They came almost as soon as I got to the carousel. I suspect that the new system in place in other airports will come with the move into the new terminal. 55 mins can be tight in YYC if you do not have nexus depending on how many US flights are leaving at the time. If its a legal connection on one ticket you should be OK. Just don't doddle getting down to the C gates.