I know this has been well covered on many sites, but I just wanted to get your opinion on which you prefer as an ereader, overall? The iPad is very convenient for short journeys, where I have the ability to quickly respond to messages and chek train times when reading. However, I still prefer the paperwhite for long reading sessions, as it is much more comfortable for my eyes. What are your thoughts? Do you use both mini and paperwhite, or prefer a single device?