I had a very rich implementation of this back in January and was pretty useful since I could implement a bunch of cool shit that clients didn’t need to know about
Discussion
Not very rich, the opposite: very rough
The part I find most interesting about rebroadcasting is you don’t even need to put your nsec on the personal server! If all it’s doing is retransmitting the event you can set up all sorts of stuff without needing permission from the authoring npub.
Even little stuff like automatically rebroadcasting an event that you reply to to your network. Something that all clients should do IMO, but you could make it happen by default regardless of the client you use.