Would be interesting to see a similar study done using the enTourage eDGe, which was designed for students/academics. It didn't catch on, but with the two screens it comes closest to providing the interactive/apps needs and the annotatable e-ink reader in one. It even allows for attachments to epub and pdf texts. I find having the table of contents on the LCD side while I read chapters on the e-ink side is almost like the "pre-reading" experience. And it helps me "map" where I find the info I want to refer to later.
The eDGe isn't perfect, but I'm surprised it isn't being considered when it clearly addresses many of the issues raised.
P.S. Thank you, Dumas, for pointing this out in the enTourage forum here.