I have arthritis in my wrist. I also have a degenerative bone disease there too. It causes excruciating pain at times, numbness, weakness and weird twitches. I have both the Sony T1 & the Kindle Non-Touch.
From my perspective - I'd say go with the Kindle. I find it easier to hold on pain days. Understand that everyone's pain is subjective and varies and changes by the day etc. What you or I may experience may differ greatly. What works for me may not work for you etc. I'm sure you know this already. Does she ever have to wear braces to immobilize her wrists? That's sometime to consider as well. If so, when holding the reader while sitting up, it's easier to press the button to turn pages on the Kindle.
The idea is for this woman to read, no? She needs it to be an easy, pleasant and enjoyable experience. Neither of the readers I have offer 3G. Kindle does in the Touch & the bigger keyboard models. I think the bigger one may be too hard for her to hold in terms of weight an awkwardness. My understanding is that the side page turn buttons can easily be accidentally pressed when holding the reader by the side on the keyboard models. This isn't the case with the non-touch. You can grab it by the side and not accidentally turn the page. I think that's an advantage.
I don't find turning pages to be a problem on either model but sometimes my hand twitches and I lose my grip on the reader. With the Sony I flip pages when I drop it on my chest in bed or accidentally press the home button or some other button on the bottom when trying to recover and grab the reader. I don't have the problem *yet* with the Kindle. It may happen but hasn't so far. The buttons are smaller and there's space between them on the Kindle compared to the Sony.
Turning pages on the Kindle is not difficult. It doesn't take a great effort to press the button, but then there's the pain being subjective thing. I think it might be easier for her to manipulate the 5 way D pad to search for books on the Kindle than messing with a touch screen on a painful, arthritically shaky hand day. You could get her a stylus to us with a touch model though. Something else to think about.
Sorry for being so long but I hope I've been a bit helpful to your decision making process. At least, it'd give you something else to throw into the mix.
