When I started at my library the Easy Readers non-fiction books were in with the fiction Easy Readers and the general children's Non-Fiction books. I separated them out, we have 50, and now they have their very own shelf at the beginning of our Easy Reader shelves.
The year before I separated them, the books went out 19 times. I separated them in December of 2011. Since then, they went out 121 times in 2012, and 112 times so far this year! So in the end, I would recommend separating them out. Why does that make them circ more? I have no idea. I can make guesses as to why. . . the main reason I would have to say is that they are easier to find. If one is looking for easy reader non-fiction they do not have to skim the shelves of the easy readers AND non-fiction, or they do not have to enter a complex search string into our OPAC.