A lot of posters will harp on paying lower interest debt as "mathematically incorrect," and it technically is, but doing straight interest-rate based paydown doesn't take into account cashflow. If using your savings to knock out the smaller loans doesn't put you in a bind when the inevitable unplanned expense rolls your way, then it may make sense. With higher incomes, it's less of a consideration, but on a more modest income, monthly cashflow is important.
+1 to the case study