[mgmueller]

To me, eBooks and the respective readers simply are a hobby, I don't use them professionally (like for example some students are doing for their notes).
And I'm actually spending more time with deciding, which book to buy in which format and then porting it to the other readers, than I actually spend for reading.
And I buy way more books, then I'll be able to read in the given period of time. I read about 10 books per month, but on average I'm easily purchasing 50 eBooks per month.
To me, it's mainly about collecting eBooks (same for paper books. I've never thrown out a paper book after having read it.). And it's simply easier and more fun, when having more than 1 unit. Some eBooks you won't find in your reader's native format(s). Some file formats have significant disadvantages (for the moment, I prefer ePUB, before that I've bought lots of PDFs because of the thumbnail view in Windows and Mac).
And each reader has its advantages and disadvantages. I've got my favorite(s) for traveling. I've got my favorite(s) for reading in the bathtub or on the beach. I've got my favorite for reading on the couch....