Entering on 09/03, yesterday, from Port Champlain (20 minutes from Montreal).
Worst experience: the Customs and Border Protection officer was upset after reviewing my AP document and Canadian Permanent Residency paper, which is stapled to my passport. He claimed that I automatically withdraw my US PR application after getting the Canadian one. I couldn't get Canadian PR because US PR took too long or just for convinence. He made copies of my AP, Canadian Permanent Residency paper, passport and said he would send them to CIS for them to make a decision. He let me go afterwards.
Please help. What will CIS do? Is there a problem to get Canadian PR while AOS?