I generally update my important docs monthly, pull down all bank statements, etc.
Yes, there are ways to get large encrypted files into an online storage, sure you could script somehting out, but the extra steps coupled with lack of ability to restore if your on a slow connection and no gaurentee that it will be there still don't make it worth it.
There really needs to be a good sync program, somehting that will work on any OS, to use the googlemail store drive, so I could rsync like another hdd, that would help with all but the restore time.