I finally renewed my library card just so that I could try out borrowing library books on my Sony and my Aluratek. Out of 5 I borrowed, I only read one of them before they expired, just because I was busy reading other books I already had on my ereader. However the two books on the Aluratek are still readable, so I might get around to them one of these days.
I can't say, though, that accessibility to library books has changed my book purchasing pattern in any way. The books I want to read, as always, are usually not available in my library system, whether as a paper book or an ebook. My reading focus is much more genre-oriented than it used to be, much of which is only available in paperback, and my library just doesn't budget for those books.
I know that the availability of ebooks and my ebook readers have resulted in my purchasing less paper books, but part of the reason for that is that I have so many paper books already in my TBR shelves. A lot of them a series books, and I've been getting the earlier books in the various series in ebook format (rather than digging them out of my boxes of books in storage) and re-reading them to remember what was going on in the stories. So I haven't been keeping up with the new paper books and buying them. I actually have some gift certificates to B&N and Borders that I've been hanging onto for months - most unusual for me.
Given the fact that any book is out there for the taking on the Dark Net, I've surprised myself by buying more ebooks than I thought that I would. I have taken advantage of the ease of buying books on my PDN with the B&N and Kindle Android apps.