> You find 9-10" is insufficient for reading material?

No, I find 12 - 13" better for reading material. The reason my Retina iPad became my default "book" is because it was sufficient. :-)

12.5" is the 'printable' area of an 8.5 x 11" page with 1" margins. (14" if you include the margins). So especially for PDFs that are 'zoomed to the margins' a retina 12.5" display can be pretty much a 1 for 1 reproduction. And that is something I've wanted for a very very long time.

Reference or casual/fiction reading?

I ask because I found the standard sized Ipad to be slightly heavy for bedtime and commute reading, whereas the small Ipad (no retina) was more pleasant experience.

I would really love a Retina quality smaller sized Ipad as long as it maintains battery life quality but considering just going Kindle for day to day and full sized Ipad as textbook / video replacement.

Primarily reference, although I recently read the Daemon/Freedom series on it and it was sufficient for that application, my wife much prefers the Nook e-paper device for fiction. I agree it can be heavy for bedtime reading but for commuting I usually have my bag on my lap and read with the ipad on top of it so I don't get any weight at all (other than the bag of course)

Personally I strongly prefer my Kindle for linear text (e.g. novels). The tablet is primarily for nonlinear and/or mixed-media reading (e.g. reference, magazines, etc)