[Saul Tanpepper]

You mean ... are there some secret algorithms that favor files from one distributor over another?

Well, of course there are!!!

I can vouch for this. I have books double-listed at B&N and Kobo, through SW and direct. The SW versions are free and the direct ones aren't, yet I sell more than I give away. Clearly both sites are giving preference to books pubbed with them directly (which is fine by me).

As for D2D, I'm switching everything over from SW, but for now am focusing on my iTunes books (which I'm not direct to).