I cancelled my subscription to Portal Feeder fairly early, and probably a good thing in hindsight as not long after that my internet marketing career took a 9 month hiatus.
I had faith that the system would eventually bring in some results, but I didn't really like the sites that were possible at the time.
I didn't provide any example sites in the past, but there are quite a few out there, and they are not too hard to find.
People using Portal Feeder tend to link through to their sites when they comment. You might have to delve a little deeper, maybe taking a look at the links page located on the site they are linking to, and then you can find lots of totally unrelated sites (quite often), and more rarely sites within the same niche with similar navigation, other than the template used. I would assume by the same author, all built with Portal Feeder.
This post for instance on the Portal Feeder blog is very typical
Some of what I have seen actually surprises me.
1. I would have expected a lot more linking, and interlinking between members of Portal Feeder, maybe with some free blogs inbetween. The sites I visited seemed to have very few linking partners.
2. By this time I expected a lot more variety in the way sites were formatted, and maybe a lot more interlinking within the content.
The good news I suppose is that the members have been active creating sites, and it doesn't take many sites, if carefully targetted to cover the cost of Portal Feeder. Many of the sites were carefully niched, rather than aiming for broader terms.
Maybe Portal Feeder v2 can do a lot more, hopefully the sites I saw were all based around v1 and that v2 sites I wouldn't be able to recognise quite so easily, and would have much better internal linking.