Both are good.
I like the ability to change the font and crop pages on the T1 which I am assuming is the same on the T2
The x50 are easier to navigate and far less prone to software failures such as the application having to close and more responsive touchscreen in my experience.
I would not replace a 650 with a T1/T2 (my T1 was a Christmas gift) unless you have money burning a hole in your pocket
but then again a new toy is always nice.
Helen