I think the Carl Sagan view would represent a great deal of evolved civilizations, but they are also the ones that likely would avoid making contact with us we are deemed ready. I think that there are beings that probably fit closer to the Hawking model, and they may not yield to that methodology… so they may be more likely to contact us first.
Look at us. If we were to hit another explosive growth spurt, the moment we get out of our atmosphere we just may be looking for Earth2. -what happens if we find it and it’s inhabited by something younger than us? Hawking has a point, as the model of our existence here on Earth supports his theory, and history can be quite a teacher. I’d like to think that the number of big picture thinkers involved in an event that more supports the Sagan ideology would be able to calm and direct the masses; but I think the fact us the first phase of chaos would invoke such a mob mentality that the general population would take 50 years to start to open their mind or adjust their thinking at all.