I'm trying out the beta with my brand new Kindle DX.
Calibre 6 is looking sharp!
Run into an issue with converting cbz to mobi (or pdf), though - although I have "Keep Aspect Ratio", the output is squished into the top half of the screen (see image).
Also, what "input profile" under "page setup" should I use for CBZ files? I tried changing it, but it doesn't seem to matter which one I have selected.