-Offer change to voters who are sick and tired of voting for the same old parties who bring no change and those who feel that the electoral system is unfair or unbalanced by changing the system to a constitutional presidential republican system.
-Resolve our divided country by transfering most legislative powers to the provinces where they belong. That way, the provinces will be free to control the very things they have battling to control for so long now.
-Bring the power closer to the people.
What makes you think the variety of parties would be any greater in a presidential republic? The example of the US system would seem to indicate otherwise.
But if you agree that provinces want more control so they can run themselves, isn't that just going create even greater differences between provinces than there are already?
Political autonomy (as opposed to cultural autonomy which has little to do with governance) is usually a reflection of dissatisfaction with the job the federal government is doing. But the whole point of the federal government is that it can perform at a state-level rather than limit itself to regional interests. Giving the provinces more autonomy would counter much of the purpose of the federation. Maybe instead of giving more autonomy to the provincial governments, you should consider making the federal government more accountable.
If by "power closer to the people" you mean that legislation reflects the wishes of the population, all I can say is that a president is still affiliated with a party and that will reflect in the policies of his/her administration regardless of whether a parliament votes him/her in or the voting public. In other words, practically the same thing you have now under a PM. It’s just that you wouldn't have ol' Liz in the background rubber-stamping everything, that's all.
(Hey when another depression causes the price of maple syrup to skyrocket to $2000 and the majority of Canadians vote for a right-wing crackpot in a desperate attempt to solve their woes, you'll be happy you've got someone who's unaffiliated who can veto it.)