I'd recommend checking them out in store. I was torn between the 10.5 or one of the new Pros. Luckily, there was one table where the new Pros were side by side, and a 10.5 was on the wall-table just behind.
The first one I saw was the 11, and it legit wowed me. Literally said it aloud. The form factor is amazing, and the screen is awesome. It felt like the first time I held a Samsung Vibrant, or the Amazon Kindle keyboard version.
After seeing it, the 12.9 felt too large to me. Sure, it's smaller than the older version, but it's still a large device. Weirdly, I think it was because it's all screen, and it still doesn't feel like iOS is meant for a screen so large. I say it's weird because I often carry a large notebook and prefer letter-sized paper to write on, and the 12.9 is approximately the same size (if a bit thinner), and it still felt big to me in ways that the 11 didn't.
The 10.5 was fine, but I definitely didn't have the same reaction to it as I did the 11.