I haven't had any problems or gitches with Sony T1. I had over 5000 on a card and it worked great. Searching for a title takes 1 or 2 seconds. Recently I reduced the number by about 1000 and moved over 4000 over to the internal memory. I like having the option to use the SD card if I want to.
I like the T1 so much, I got a 2nd one last week. I only have about 500 on it now. It's nice knowing I can put thousands on it with no performance issues. Can't do that with my Kindles.