I'm interested in this discussion. Clearly, you want to assist those who need it most, and you want to do it in a way that's fair. Yet you also want to do it in a way that's simple. In other words, you want to keep the administrative costs and the complexities of it as low as possible. One of the advantages of the present system is that it is tied to an existing measure that's very straightforward and simple.
It strikes me as well that you'll have cases where two kids from the same community may go to different universities, may go away somewhere to university. Now, that's harder and harder if you're low-income, clearly. But if one's going to Carleton and the other is going to a smaller town, let's say Antigonish, Nova Scotia--my alma mater, St. Francis Xavier--those two are facing very different costs, even though their families, with the needs-based assessment you're talking about, would warrant the same benefits, the same grants.
Maybe there's a way to work this out that makes sense.