As BFTUK said unique content is a must, more than just having unique content the idea of student essays/dissertations works for a few reasons, its long tail search words your looking to get traffic for. You don't have the time/energy to
SEO each domain or do more than put a link to it so the actual content QUALITY used is very important.
You don't need to worry about single keywords or difficult ranking keyterms, the idea is to pick up traffic from long tail phrases that are specific and your quality unique content can catch.
For example I paid someone to write articles for a site
Home & Office Furniture the quality of the articles is crap and that reflects in the crap traffic to it, having some unique content alone wont get you much IMO.
I then (lived & learned) paid someone to write some articles about tattoos for
Tattoo Info, now I asked a tattooist to write the content for this site, $10 per article ~ that site gets traffic mostly from google, its not a mini site but one made quickly with a script and paying for quality articles.
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So I'd vote against article sites, cutting up content trying to make it unique and find a source for good quality content/articles, when you do you can throw up 10
mini sites in under an hour, 10 sites that should be able to much more than pay for themselves. That's my take on it if it helps anyone.