[fjtorres]

Some people are compulsive hoarders.
They grab everything they find simply because it is available not because they are going to consume it.
The real "threat" are the commercial pirates who monetize those "unauthorized editions".
One particular pirate site highlighted in a Cnet antipiracy report (thereby driving traffic to the site) cheekily lists pirate epubs for download next to a link to buy a legal copy for Kindles.
Others merely host google ads and monetize the downloads that way.
Those folks are not going to be stopped by switching DRM; if anything, they can afford to scan and ocr print editions with professional grade gear.
As with classic napster, the only way to minimize downloads of "unauthorized editions" is by offering readily affordable legal editions. Piracy will always exist, especially if by obsessing over it the publishers drive customers away by penalizing legal behavior. But it can be minimized by treating customers fairly.