I have a 600 and the Tuff-Luv cover for it is too big for the 650. If the 650 is all the way down, it cuts off the status line. They have one for the 650 that is available for preorder, but they show a picture of the PRS-600. I'm sure they've done the same thing for the PRS-350 cover that is available for pre-order as the picture for it is for a PRS-350 and they are nowhere near the same.
I'll be ordering one of their covers for my PRS-650 as soon as it is available on Amazon.