The only impact it makes as far as I can tell is that it doesn't lock when I close the "smart case" cover, the screen stays on. Not really sure why that would be desirable. I'm confused by these lock settings. As I said before, I would like it to lock after some defined duration when unplugged but never lock automatically when plugged, maybe some day.
And while I'm on my wish list, I hope that iBooks catches up with Kindle's reading experience -- Amazon has much better annotations, notes, textual analysis, Goodreads integration, statistics, etc.