On my e-book site, I sell my books in multiple formats, including PDB for eReader, and a seperate PDB for iSilo (among others). I've just noticed that, after a year, I have sold NO iSilo PDB e-books at all!
Now, I know that I'm not exactly selling to thousands here (or even hundreds... or even... well, never mind

), but should I consider this a trend? Are there fewer iSilo readers out there now? Are other formats winning out? Should I drop the iSilo PDB in favor of another format?
Opinions are requested.