Backup without erasing?

[dnanian]

I don't think so, actually.

For one thing, the Safety Clone does not copy your user files. It links to them, on the original volume. As such, it's not a backup at all -- it's more of a checkpoint of your system.

On top of that, you can only do the "Copy Newer" one time. Future attempts to update the Safety Clone will not guarantee bootability, or even a very valid system, because things won't be copied properly...

I really don't think you should be doing this... you should partition if you're going to attempt more advanced things like the Safety Clone.