I recently completed a Masters. Just in the last year or so, some of the textbooks became available in electronic format. However the format was non-standard and special software was required for reading. This was not indicated on the sales site *before* buying. I knew, thanks to a fellow student who found out the hard way. I installed the software on both my tablet and my laptop, and used it on both, but I've hardly ever used my eink reader for anything other than leisure.
I've just started another Masters and have been reading a lot of scientific papers. Again, with pdf the tablet comes to the fore. But my T1 goes everywhere with me so I have something more relaxing to read on the bus.
Personally, I think that choice of device won't make that much difference as to a person's self-discipline. Even if textbooks are available in epub/mobi, what would stop someone from procrastinating by switching to reading a novel instead?
Finally, regarding the profiteering professor conspiracy - I once had a professor who was so upset about the high price the publisher had set for his textbook that he made sufficient copies (pbook) and gave them out to everyone in the class for free.