I traded in my 505 for the 950 (don't have the 505 anymore to do a side to side comparison). For text, I feel the 950 is "snappier". I feel for PDF, it is much more noticeable. I remember that I used to hit the next page button 1-2 sec before I reach the end of the page on the 505. So when I really at the end of the page, the page turn timing is just about right to continue reading uninterrupted.
I dont have to do it for the 950. Reach the page end, swipe and continue.