I don't use ROM Toolbox Pro for my full backups as they've never worked when I needed to restore my phone for some reason. I just use Titanium Backup + Carbon for that. Haven't really relied on a full image backup anymore as I just make sure I keep a previously functioning ROM that I can flash and restore with the aforementioned combination of apps.
ROM toolbox does have a nice boot-animation tool that allows you to customize your boot animations super easily, and with a lot of animation options. They have kernel controls, adblock tools, and a bunch of other options that I would say are worth it if you're just using that tool alone to provide a host of functions for your device. The adblock works well for devices tethered to your phone, as it's hindered many a Hulu-watching session, so I had to disable it.
I don't use it anymore, as I've switched over to apps the serve one specific function, like Titanium for APK restores, Carbon for app data, Franco kernel for performance control. I don't use the boot-animation feature anymore, which is what it was essentially relegated to after I developed a workflow for crack flashing using other apps.
Can't really justify it myself, but the combination of cost for other apps that provide similar, but singular functionality is much more expensive. But I would recommend supporting those developers if you find you use them often anyway.