&gt; I doubt most Kindle users even know there's DRM there. 

You under-estimate your audience.

&gt; As to the brief period a book attracts a hardback price
&gt; before being cut to the paperback one...
&gt; that's been custom and practice for decades.

I was not criticising the printed book price model. That's perfectly reasonable. I was criticising the ebook pricing model. Linking it to the price of the current print edition is 'old model' thinking, and exactly the error the music industry made before it started to build business models for the digital economy, and companies such as Spotify appeared.