Lynx, perhaps I have injested too much cold medicine but I don't understand what you're asking. Change for the T1 from what? The 650? I think it's part of the Reader for PC & the new readers. I don't believe it does it automatically for the x50's. I had a 350 at the time the T1 & the new Reader for PC came out and it didn't do that.
The Sony T1 when connected to your computer with Reader for PC running automatically starts syncing every single book in your library onto your device. I don't want that. In fact, I hate it. Even if you try to stop it it's already made changes to the way your books are set up on your device. I've never been fast enough to not have that happen.
How do you get your books onto your device? I do not use the Reader for PC for that. I either use drag & drop or download on the reader itself or use Calibre. I won't use Reader for PC to get books onto my reader because it makes a complete mess of it.
There are several old threads from when the T1 first came out with what Reader for PC does in the way it syncs to the device. I have not and will not take the chance to connect my device with Reader for PC running so I don't know if it's changed but somehow I doubt it. It'll still do the auto sync nonsense which I do not want.