1. A P3 arrangement is best suited for public infrastructure that has already been built but needs to be maintained or replaced over time. There are a number of reasons for this, but the biggest one is that a P3 should never be used in conjunction with an eminent domain process to forcibly acquire property from private owners.
2. I would never invest in a P3 contract for a highway project, which is ironic because these are the ones that have been most popular in the U.S. I just see an enormous unknown risk of civil liability in controlling a roadway in a country where more than 35,000 people are killed in motor vehicle crashes every year. I suspect this is why the big toll road lease deals that were done in the last decade (including the Indiana case cited in this article) involved foreign investors who probably never even considered this aspect of it.
3. A P3 arrangement is mainly a financing mechanism, and should be treated that way by all players involved. What makes them attractive to a conservative like me is that they help promote a "user pays" environment that should become standard across most public expenditures.
4. Along these lines ... you'll see a landmark shift (for the better) in this country once P3 arrangements become commonplace in one of the most disastrous institutions this country has: public education.