Another digi publishing blog I've just come to which might be of interest. Stephen Leather is successful in paperback as well digital, but Kindle seems to suit him.
The dominance of crime and thriller writers in the Kindle charts is extraordinary, something he touches on here. Perhaps it reflects the "disposability" of the genre - you seldom want to read a thriller twice because once you know the end the trick is gone. Therefore, why bother with a hardback etc? Just a thought.