E.R. Campbell said:
In my opinion Britain and Canada, like Britain and Australia, are drifting farther and farther apart. We share a valuable, indeed Great common history but we do not share a common future, except as equal partners in the Anglosphere. Charles will be, even more than his mother, a distinctly British monarch who will be used, effectively, by the UK government as e.g. a trade promotion celebrity - a UK trade promotion celebrity; we don't want or need the King of Canada to be dashing off to the USA saying, "Buy British." Most Canadians cannot distinguish the Throne of Canada from the Throne of the United Kingdom and from the Throne of New Zealand - it is pointless to blame anyone for our constitutional ignorance, but we don't need to complicate the issue by sharing a monarcyh who has very, very little personal connection to and, I suspect, even less interest in Canada.
A Regency means that our Constitution remains absolutely unchanged - not a single comma needs amending. But our sovereign is a Canadian, selected, as Anglo-Saxon monarchs were 1,000 years ago, by some sort of council of elders - maybe our Parliament, that's a minor technical detail.