I installed Syncdocs. It worked just like it should have. Very good idea.
I was changing a lot of document names and sharing properties in Google Docs, so I expected the syncing to be busy - but not as busy at it in fact was!
I couldn't understand how come my bandwidth utilisation was going off the scale, until I realised that that for every "Collection" in Google docs, there is a corresponding Folder created on the client (backup) hard drive. "Collections" are in fact not proper "Folders", but categoristion tags under a different name.
Lots of my docs are/were categorised under various "Collections". So, if a document was tagged into (say) 5 Collections, then syncing caused 5 copies of the file to be dispersed across 5 Folders on my hard drive. Duplication big time.
So I switched the syncing off. Maybe I will only let it sync once a week.
If I had left it on, then it would have blown my bandwidth cap in no time, given the rate I was changing things.