The source control made accessible due to Teletype is nothing short of awesome, but it’d be great if it shared all the files in the project of the host rather than just the active tab. If anything, possibly adding the project with the client to browse through to edit would be awesome with special arrows or highlighting to show the host/client which file the other(s) are working on.
Also implementing some form of chat between the host and client to communicate over the project in a tab would be helpful in case you are not face to face with the client. So far, my way around this has been talking through comments in the code which is a hassle sometimes but its okay.
Overall, my impression is Teletype an awesome package with great implementation!