Actually, the super visa was created in order to help decrease the stress of families not being able to be together while they waited to get their PR application reviewed (and accepted or rejected).
So, alot of PR applicants that already have their applications in an advanced state and possibly nearing completion (in a year or two or three) are now getting the super visa, and coming to Canada to wait for their PR status to be approved (Its a ten year maximum, multi-entry visa that allows visits for up to 2 years at a time). So now, someone's 77 year old mom can come and wait here for a couple years and at least get to know her grandchildren before a) she dies, b) they grow up, c) her PR visa gets rejected, or d) her PR visa get approved.
I have even heard of some applicants that have applied for the super visa for their parents, to see if they like it enough (can last all winter!) to apply for a PR visa. People are not prohibited from applying for a PR visa just because they already have a super visa. Not at all. And they won't fall between 'the cracks' any more than someone else (overseas) will.