I didn't mean to imply any advantage, just that they are another socket-based method for two processes to communicate. Since vsocks use a distinct implementation they should probably be benchmarked alongside Unix domain sockets and loopback sockets in any comparisons. My expectation is they would be somewhere in the middle - not as well optimized as Unix domain sockets, but with less general overhead than TCP loopback.
If you are using vsocks between two VMs as intended then they have the advantage that they allow communication without involving the network stack. This is used by VMs to implement guest agent communications (screen resizing, copy and paste and so on) where the comms don't require the network to have been set up at all or be routable to the host.
