Sorry for the late entry into this one but here is my take on the whole ROM Manager thing. While I think that its great that the devs made a great utility to help root users download ROMs and such it isn't worth the headache. Like if you do in fact make a backup with it, would you really know how to access it if you soft brick your device?
My point here is that ROM Manager is just something that is an illusion of safety. Yes, you can use it to download and flash ROMs, do backups/restores and many other functions but if you ever get stuck in a boot loop or something like that, you are stuck. Unless you know how to work around the manual recovery then you will be in a panic.
Whenever you are going to rooting/hacking your phone you should always get to know your custom recovery... I may be saving your but one day.