Make a 'russian doll' arrangement with your disks - put your smallest disk in the most-used computer, and make full backups of that disk on the next-larger disk, etc.
For example I have an 80gig disk (SSD) in my MBP, its the most-used disk .. I can back this disk up 5 times to my 400gig external hard disk (full disk image each time) .. to do a backup I boot from the external disk, which has a minimal OSX install on it just for this purpose, then I make a full disk image, save it, and reboot.
You can significantly improve the odds of recovering all the data if you use at least 2 backup strategies. Like Time machine + SuperDuper full disk dumps
I've been using Time Machine over an open VPN (Tunnelblick) bridged network. I also backup really important stuff with Arq to S3 at reduced redundancy. This ends up costing me about $25 a month. But I can sleep known that if my house burns down or a burglar steals all the computer stuff in my house, I won't lose anything.
But I agree, it is not fool proof and may just help in propagating errors.
So what is a good backup strategy?