I sent mine via Priority from Mount Pearl, Newfoundland on Monday (July 11). Fort Erie received it 7:45 AM Wednesday (July 13).
On Friday (July 15), the tracker for the return Xpresspost envelope I gave them became active. It doesn't give any useful information, just the automated "Item delayed" message that every single package is being scanned in with right now because of the backlog. But that seems ridiculously quick, since it would mean Buffalo only had my passport for 2 days (if that). So now we're waiting to see if it's just a glitch in Canada Post's system or if my passport will be back here in just a couple days.
.