Getting a new fresh domain on the first page can be a pain in the ass. You only have to do one thing wrong and your domain lands on page 100 or in the google sandbox (google confirmed the existence of this). That said, it is possible to get a fresh domain on the first page quickly but that requires major knowledge of SEO and knowledge of the many google quirks. The difference over the long run, i think not much. But maybe it's me, but i don't want to wait months to get quality traffic.
That's only the domain story, let's look at the linking story. Putting x domains on a single server and interlinking between them isn't a wise thing
But interlinking between x domains on your server and x blogs on thumblogger can give PR a big boost. And of course traffic, 1 blog in the search results give less traffic then 10 blogs in the search results, but that's logical.
And there are even more tricks to be a better blogger.
