I have both. I love my 350 & it goes with me everywhere. Fits nicely in my purse with it's cover on. It is easy to side load books to the 350. I don't find the small screen a problem. And until I got the T1 I pretty much read on it exclusively. I don't have PRS+ but many love what it does for fonts.
I also have the T1. I like the size & that there is more to choose from for fonts & font sizes without having to root it.. Makes a difference for me in the evening after a long day of using my eyes.
I have never filled up a reader with books. But then I tend to delete ones I know I won't be reading again. But still in the year I've had my 350 I've only put around 200 books on it. And I do read a lot (also have a Kindle)
I doubt I will ever use audio so it's not something I can comment on.
Gecko has a nice cover with a slot for the stylus if you should go for the T1.
I tried the browser on the T1 & it's okay but not something I will likely use again. And the Sony Store via wifi is nice, but I will more than likely sideload books like I do with the 350 since I like other stores better.
In the end it is really what you find you like the most. I ended up with both, but then I like to try out e-readers. In the end, all have things that are positive & all have things that are a negative. But I don't think you'll go wrong with either.
P.S. I too bought an extra 350. Of course I don't know what I will do if the batteries fail.
