CJ Lyons has a very business-like breakdown of whether Amazon KDP Select can work for you or not. I love this sort of level-headed examination, free of hype or drama. Great stuff:
“In my own experience, both times I tried Select, my lends were neglible compared to other authors. But as I polled other authors, I realized that the lending trends fall into two groups: relatively unknown authors were receiving higher numbers of lends while more established authors weren’t.
My guess is that the better-known authors with established series, good reader reviews, and bestseller status were actually being bought rather than borrowed. In my case, I could calculate the higher number of sales I received via Select and compare it to the lends as well as what I would usually sell of those titles via other venues.”