I think you're correct. The P3 is a really good method to shed some risks from the public sector onto the private sector, if properly accompanied by proper agreements that ensure you are actually shedding those risks. It does come at a cost. It's not like a free system either.
In the case of our biofuel, one of the key drivers for that project to be a very suitable project from a P3 perspective was the fact that internationally we had a lot of technologies competing to produce fuel from our organic waste. It was very hard for the city to fully determine which of those technologies would be successfully built and successfully operated. By doing the thorough P3 process, we were able to determine which team—which consortium, essentially—was going to be entrusted with delivering the gas at the end of the day, while not taking any kinds of risks on the technology. Of course, that comes at a price. You have to pay the private consortium to take those risks, but at least you know what you're paying and what you're getting.
That's an example of where a P3 is well suited. It has to have a significant component of innovation, expertise, or shedding risks, because there are some inherent costs with the P3 system.