Originally Posted by tubemonkey
The 8.9" Fire has a higher resolution display - 254 ppi vs 216 ppi.
It's pretty addicting too, for me. The processor is also faster.
Mainly, it's big enough so that Amazon felt they could offer the 2-page book if you turn it to landscape. Since you can increase or decrease the font size, line spacing, etc., it makes the two page layout really nice. I read faster when I have nibbles instead of a large page of text and my mind sees what is left.
Probably takes more battery to turn the page more, but I like the two-page layout a lot and find myself using that all the time now. Go figure, since I did love the DX for all that it could put on a page.
I use the KFire 8.9 for sheet music too and, as with PDFs, they're FAR more readable on the larger size tablet. Sheet music especially. But, it's the 7" I carry around when going outside. So if portability is more important, I'd go for the 7".