@Shopaholic I left out that I'm referring to the 650 and Reader for PC, lol
after I download every book in Reader for PC ( or Kindle for PC) I then import them into Calibre and clean them.
Then I use any of the methods to get them onto my devices: drag/drop, Calibre connected to device to send, or use Dropbox etc for Kobo and Playbook.
Yucko if it's compulsory sync from the T1 model onwards
The Kobo desktop does the same, so I've set up 2 Kobo accounts: first account is my primary account which I use to buy the Kobo books; and the second account is the account I only use for the device, and therefore sync with Kobo desktop when there's a software upgrade.
So - the first account buys the books, but I don't ever use that with Kobo desktop.
I only use the second account (which doesn't buy books) to sync with Kobo desktop.
Maybe that's a way for you to consider with Sony as well?
It seems that when I upgrade my Sony I'll also have to have a second Sony account and do that.