I would say the most important position is PG followed closely by SF. You had some interesting points about SGs but to be honest they are a dime a dozen. PGs still need a lot of outside d, jump shot and jump range to be effective. A PG who can only pass the ball is really not very useful in my opinion.
With a very balanced SF, you can mix up your offense and defense however you want. Plus you can play a man d and have no fear. Without a balanced SF, if you play a man d you are either opening a hole on outside or inside d.
Run of the Mill Canadian Manager