Use Sugarsync as cloud.
If setup, once you take a picture, it automatically uploads to cloud AND your PC. On your PC, set up the Pictures folder to sync to Sugarsync. Then on both your devices, sync the Pictures folder from cloud to your device. If you arrange the contents of your Pictures folder on your PC into subfolders, these subfolders will sync with BOTH of your devices and will appear in your galleries as albums. Any changes made in one device (PC, tablet or phone) regarding these folders (such as adding pictures or deleting) will reflect on all three.
Regarding backups, if the devices get formatted, the sync folders will not be affected. However actually deleting the files from the device will delete the file from the synced folders on both PC and second device as well. Sugarsync however has a "deleted files" database accessible on their PC client, from which you can restore any deleted file, so they won't really be lost (unless your sugarsync account got filled up and there isn't any more space for deleted files to be kept on archive).
A couple of catches however. Syncing this way will force the albums into the internal SD of your Android, inside the MySugarsync folder. You cannot have them in another place. So if your phone has a small internal SD, you're sort of screwed. But I see you have a GNex, so you don't have any other storage anyway. Also, If you make changes using your phone or tablet, this will not affect the "mobile photos" folder in your PC, and this will cause duplicates of photos on your PC ONLY, one in the mobile photos folder, and one in the album folder that syncs.
EDIT: It doesn't have to be actually the Pictures folder you sync. Sugarsync allows you to select ANY folder on your PC for syncing, so you can make a folder named Android Photos or something and use that for syncing.