Their is more to the the dongle broken payloads then this at the moment.
The payloads add some syscall's that have not been implemented in this firmware mod. That means that their is more to it then just signing the current backup managers as they rely on custom hooks implemented by the payload devs. This is however a nice proof of concept.
I am assuming it also allows for retail updates to be applied to games you have the disk for as well, which is handy for those who do not have a net connected ps3 and want some of the bug fixes available.