Hey - I thought I answered this, but it looks like I didn't. I have about 150 volunteer hours with two different ages but similar populations (adults with aphasia, children with developmental disorders). I was told by the student coordinator at U of T (Robin) that whether or not they even look at the volunteer section of your application depends on the specific person reviewing your application. They really aren't taking it into consideration for the most part. Last year, I put all my work experience into the volunteer section (and wrote in the description that it was paid), but this year I didn't bother. They are really looking at the combination of grades, references, and a kickass statement of intent.
Good luck!