You will have to come to Canada for the test/interview and the oath, and they won't give much notice on these, meaning you will have to buy tickets/plan travel last minute for these.
Also, they will only mail information to Canadian address, as I have read here (I may be wrong), which means fingerprint requests and anything else they need to mail to you for whatever reason won't reach you/will be severely delayed if you have people who have access to your Canadian address.
other than that, I don't think there are any bureaucratic issues with this.
Of course, they might be curious as to why you applied and left Canada and, depending on your whole story, that might bring in more scrutiny on your physical presence days count etc