I still think you’re going to cause a new form of sculpting, where people will remove links from their pages other than using nofollow, in hopes flowing PageRank to links they think are important. You’ve said number of links matter — and that nofollow doesn’t reduce those links — so some will keep chasing after whatever extra oomph may be out there.
One final note is that if the links are not directly related to the subject, or you have no control over them, such as commentors’ website links, maybe you should consider putting them on another page, which links to your main content. That way you don’t leak page rank, and still gain hits from search results from the content of the comments. I may be missing something but this seems to mean that you can have your cake and eat it, and I don’t even think it is gaming the system or against the spirit of it. You might even gain a small sprinkling of page rank if the comment page accumulates any of it’s own.
But bear in mind that you can't guest post just anywhere and expect that it'll help. In fact, for years black hatters have perverted the value of guest posts by 'creating private blog networks,' which put out mass quantities of low-quality content for the sole purpose of exchanging backlinks. Google has caught on to this, and penalizes websites accordingly. So, you want to ensure that you only provide guest posts to reputable, respected websites that are relevant to your industry.
I always like hearing a new idea for beefing up the number of backlinks to a website. The fact is, creating backlinks is hard work. There’s always that urge to look for a better way to do things. Just keep in mind that Google is always on the lookout for anyone who might be trying to “game” the system. Google’s algorithm, especially, looks closely at how relative the content on both sites appears to be. If there’s a close match, it’s a good link. If not, the backlink may appear to be a little suspect!
In the past, the PageRank shown in the Toolbar was easily manipulated. Redirection from one page to another, either via a HTTP 302 response or a "Refresh" meta tag, caused the source page to acquire the PageRank of the destination page. Hence, a new page with PR 0 and no incoming links could have acquired PR 10 by redirecting to the Google home page. This spoofing technique was a known vulnerability. Spoofing can generally be detected by performing a Google search for a source URL; if the URL of an entirely different site is displayed in the results, the latter URL may represent the destination of a redirection.
I like that you said you let PageRank flow freely throughout your site. I think that’s good and I’ve steered many friends and clients to using WordPress for their website for this very reason. With WordPress, it seems obvious that each piece of content has an actual home (perma links) and so it would seem logical that Google and other search engines will figure out that structure pretty easily.
Can I just remind Google that not all “great content” is going to “attract links”, this is something I think they forget. I have great content on my site about plumbers in Birmingham and accountants in London, very valuable, detailed, non-spammy, hand-crafted copy on these businesses, highly valuable to anyone looking for their services. But no-one is ever going to want to link to it; it’s not topical or quirky, is very locally-focussed, and has no video of cats playing pianos.