Whip me, beat me, make me maintain ....
Dag, we can't blame you for being brainwashed by IBM and still looking back at AIX tools, afterall you worked there twice already and who knows how may more times to come :)
But .. before you start to reinvent the wheel, or mksysb have a look at the following tools.
There's 2 tools that come to mind when looking at your requirements.
A tool I used a lot about 5-6 years ago is Mondo Rescue :
Mondo Rescue is a GPL disaster recovery solution. It supports Linux (i386, x86_64, ia64) and FreeBSD (i386). It's packaged for multiple distributions (RedHat, RHEL, SuSE, SLES, Mandriva, Debian, Gentoo). It supports tapes, disks, network and CD/DVD as backup media, multiple filesystems, LVM, software and hardware Raid.
I haven't used it for a while since my current preference off course goes to the SystemImager Framework. Apart from using it for automating installations off course you can use it to create a golden image of your running environment and restore that image any way you like, over network, from CD (with si_mkautoinstallcd) etc.
SystemImager makes it easy to do automated installs (clones), software distribution, content or data distribution, configuration changes, and operating system updates to your network of Linux machines.
On the other hand , if you manage your systems in an Infrastructures.org way , and you have good backups of your data. You don't need to restore a system from some media, as you will just be able to rebootstrap the failing machine in an identical way as you have been managing it and the only thing needed to do is restore your data.
PS. if you don't know what I don't want to maintain, skip the first result