[mistermann]

Can each of those be turned on or off per device, and dont get sneakily turned back on during upgrades?

[johnchristopher]

edit: Sorry for anyone I misled. You can't opt a particular kind of data out of syncing per device. You can only enable/disable for the whole account.

Yes, each (bookmarks, history, passwords, tabs ) can be turned on or off per device basis.

[mnoorenberghe]

This is incorrect AFAIK. The sync toggle for a data type is for the whole account, not per-device.

[johnchristopher]

You are right. Always thought it worked like that but indeed it is for the whole account and not per device. My bad.

[maximente]

by way of logging in/out, yes