I connected through YYC yesterday and thought I would provide a brief report on the experience, which went much better than I expected.

• We arrived on a Sunday morning around 11:15. Our flight from YEG landed at one of the farthest A gates, and our next flight to ORD left from E88. The connection process was complicated in that there were a lot of steps, but it moved relatively quickly. There were four of us, and we moved a bit more slowly than I would have on my own, but the entire process gate to gate took about 45 minutes. That included several of being being delayed for extra screening of our carry-on baggage, and two of us having to wait about 5 minutes for checked luggage to clear customs.
• The Air Link service worked great for us. We got lucky in that it pulled up just as we reached the pickup point at the A concourse and we got the last seats on the 10-person cart. Once I saw the distance we traversed, I was glad we had not opted to walk. (It's certainly walkable, but it's long enough that unless you have lots of time or have been there before, I could imagine it being a bit stressful. Plus, we still had a decently long walk after getting dropped off. ) I note that because the 10 people waiting at the A concourse were all going to D/E, passengers who were waiting at the B and C stops were required to wait for the next cart. I'm guessing this may be a somewhat frequent occurrence, so perhaps Air Link works most reliably for folks landing at the A concourse.
• The security screening for the D/E gates was not very crowded at that time of day, and there was virtually no line at all in the US Customs section.
• Despite the lack of crowds, the initially security screeners at the D/E concourses were notably unpleasant, continuously yelling at people rather than providing actual useful guidance. The guy standing behind the bins saw my square quart-sized bag of toiletries, and required me to empty it and repack the contents into the rectangular-shaped liter-sized bag provided by CTA. While the volume of the two bags is virtually the same, due to the different shapes not all of my assorted bottles fit inside the new bag. I was nonetheless able to place it in the bin so as to disguise that fact, and it passed muster with the person who was doing the actual screening. I wasted 5-10 minutes on this stupid exercise, much to the chagrin of the other CTA agent who was trying to move people quickly through the line. My laptop was eventually shunted aside for secondary screening, and the person in charge of that process was much more pleasant, but inspected it with a degree of thoroughness that suggested this was a foreign object she had never previously seen.
• By contrast, the subsequent process for "clearing" our checked luggage through customs was remakably fast and efficient, in addition to being friendly. The agent scans your boarding pass and if your luggage has not yet cleared, you are asked to be seated in a small comfortable waiting area with chairs. Once your luggage is cleared your name pops up on a television monitor alerting you that you can now get your boarding pass re-scanned and continue on to your gate. As noted above, 2 out of our group of 4 did not initially clear, but were cleared within 5 more minutes.

Again, this took place on a Sunday morning in mid-May, when the airport was relatively empty. YMMV.