I really appreciate that KOReader is an option. On my older Kindle (first-gen Paperwhite), the default reading experience had declined until page turns take several seconds. Firmware update and factory reset wouldn't fix it. Using the default reader just wasn't a viable scenario.

I jailbroke it, launched KOReader, and it's like I have a new e-reader. The amount of customizability gets kind of in the way, but once it's set up I don't really think about it from one month to the next. I also didn't feel the need to upgrade my original install either.