I understand this is an old topic, but I hope my information will be useful. To answer topic starter's question: ultimately, it is your decision whether you need Canadian citizenship or not. I think having multiple citizenships is very practical but can get very problematic to maintain to maintain the residency status (especially in the US). I was in the same situation 4 years ago: we got our US Green Cards and left for the States. On our way to the airport we dropped our Canadian citizenship applications in the mailbox and then kind of forgot about it, although I did check our process status online from time to time. After approximately 1 year we were called for a citizenship test, which we passed but we got RQed due to the fact that we had US immigration Visas in our passports. We submitted the necessary paperwork and after about 1 year we were invited to the ceremony.