It's been very useful for specific things: unified, complicated domain logic that benefits from running faster than it would take to do a round trip to the serv

It's been very useful for specific things: unified, complicated domain logic that benefits from running faster than it would take to do a round trip to the server and back. I've only rarely needed to do this. The two examples that stick in my mind are firstly event and calendar logic, and secondly implementing protocols that wrap webrtc.