I noticed an interesting effect recently from a site I used the SAPE network on.
I launched a website last December covering a large topic which required many keyword targeted pages. After a few weeks I launched a SAPE campaign targeting one of the core keywords. Each SAPE link, all 150 of them had the same anchor text. What I noticed is that Google increased the overall ranking of the site, more specifically the target keyword. However, I noticed that a lot of other keywords begun dropping off.
I personally believe this to be a case of weighted relevancy. I believe the site to have become lopsided concerning relevancy. The anchor text likely told Google that the site was super specific to that keyword and as a result other keywords begun dropping.
Other evidence which strongly suggests this is the case is that weeks after removing the SAPE links, the keywords which dropped off actually begun increasing in rank until I now had a nice balanced level of ranking across all keywords.
This is nothing to do with SAPE as a specific service, this is about how Google might treat relevancy of a site based on anchor text. If all of your anchor text and high value links specify "Blue widgets" then it could be that "Red widgets", while still relevant, is pushed out because of the overweighted relevancy your backlink profile is giving to "Blue widgets".