One thing that's distinctly better is that the backoff/recovery behavior of SSP (mosh's custom encrypted protocol, over UDP) works a lot better than TCP's. If I'm typing, and there's a network blip for e.g. thirty seconds (cell handoff), SSH will literally take minutes to get back to normal, and it'll be easier for me to kill SSH and restart the connection. mosh will recover much more quickly. TCP was written in the days when congestion on a shared Ethernet segment was a thing people actually ran into; with wireless and cell networks, that's not actually your protocol's biggest concern.
The common-case latency, when there's a good network connection, shouldn't differ much.
The common-case latency, when there's a good network connection, shouldn't differ much.