Ranked in these QuestionsQuestion Ranking
Pro Compatible with multiple systems
mtm emulates a classic ANSI text terminal. That means it should work out of the box on essentially all terminfo/termcap-based systems (even pretty old ones), without needing to install a new termcap entry.
Pro Very lightweight
mtm is small. The entire project is around 1000 lines of code.
Pro Very stable
mtm is "finished" as it is now. You don't need to worry about it changing on you unexpectedly.
Pro Easy to use
There are three commands (change focus, split, close). There are no modes, no dozens of commands, no crazy feature list.