I know this is a strong statement and will line this thread up for flaming. But IMHO PBN as a ranking strategy is nearing oblivion. Why is say that? because PBN has become a mainstream strategy and any strategy that becomes mainstream is hit by Google sooner or later. You can look at history and see for yourself, right from stats hitting (aka links from website stats like awstats) to Blog Networks (BuildMyRank) and Penguin, any technique that has become too mainstream is hit by Google. The follower of the technique always say that Google can't hit that technique (like they said in blog networks) and its almost infallible. But, the truth of the matter is Google has so much info from so many sources that it can hit any technique it want, the only consideration is how much collateral damage will it cost. If you are doing PBN for some time, you would have seen that PBNs are not as effective as they were say 6 months or 1 year before. They are still very effective but the ranking is not immediate and it increases gradually. That shows that PBNs are on Google's radar and they would be working on something or the other to take them down and they will not take it down gradually, they will unleash one monster update that does it in one swipe, to shock and awe the seo world. Why? Because the fear is much better weapon to stop any technique. They can't take down 100% of the sites, there would be sites which will go under the radar, but they only need to take down 60-70% to cause big enough splash for people to fear any technique. So, IMHO if you are relying only on PBN links then start diversifying as its the only way to fly under the radar. I am not a fear monger PS: I don't have any insider information, just what I feel from the underlying pulse of the market. I also don't know when the hit will come, it make come in next update or it may not come for 2 years, but better take precaution than sorry.