Yeah, I'm a couple of weeks late, but ...
I still have my K2US. I don't use it for my own reading pleasure, but I do use it to make sure that ebook creation techniques I'm employing aren't going to leave people who ARE still using them out in the cold. The way I figure it: if someone with an older device CAN buy your book for their older device, then you owe them the best experience you can give them on that device. I'll write those devices off when those devices can't be used to buy new books from Amazon.
