I would be very careful on going out and re enter canada. Here is a post where i just wrote my experience, maybe it can help you too
http://www.canadavisa.com/canada-immigration-discussion-board/extending-a-visitor-visa-in-order-to-be-able-to-apply-for-common-law-sponsorship-t193653.0.html
Hope is ok to give you this link since I dont think i should repost it here, it not all applies to your question.
In my case asking for extended stays has been the successful way to go however i am applying common law so i had to be here for more than a year.
If when you come back you have to face an immigration officer asking questions like i did it might get complicated, at least in my experience i would never risk that again, it was a bad one and i got really lucky. Hope it helps.