You should be using file backup on any system with code on it. It is so cheap to do this today, it is a no brainer. Apple Time Capsule, Crashplan Pro, etc.
Come at me, bro.
My point was that pushing constantly as a backup mechanism isn't an option if you intend to rebase frequently (unless you're the only developer on the project).
The D in DVCS is all well and good, but there are business reasons for having a canonical store of all source materials.
Backup is good because it's automatic. Saving somewhere else is nice too, but it's not really backup.