So, Smashwords has what, less than 1% of the ebook market right?
I'm not sure this will tell you anything too cogent about Smashwords' customer base, except that it's probably a good idea for authors to offer their works in ePub, PDF, Text and MOBI formats, or else you might leave a good slice of customers in the cold.
Otherwise, it certainly doesn't tell you anything useful about the market at large.