Hi, I've been here going on six years now. When I left Canada, I "severed ties" which is basically what the other poster was saying you need to do. This means club memberships (or taking up a non-resident status), not maintaining a residence such as cottage etc. Since I have been here we have bought some property back in Canada, but it is rented at arms length and we file NR-6 which is a declaration of rental revenue by a nonresident. You can get a lot of this information from Revenue Canada's website.
My employer put me in touch with a tax specialist who looks after filing my taxes here as well as in Canada (even though no income there) and it's all pretty clean.
If you have an RRSP you can leave it in place, but cannot make any contributions. The only benefit to collapsing it and moving it offshore would be if you are going to be here long enough to earn significant returns to compensate for the Canadian tax it would have attracted.