If recent customer requests for Git training are any indication, this popular, free, open source tool for managing source code is gaining momentum and will soon be mainstream on IBM i.
Rational Developer for i (RDi), the modern editor for IBM i RPG, COBOL and other languages, runs on Windows and Linux, but not Mac.
IBM has shown some willingness to port the product to Mac. They have posted a poll to allow users to vote for this enhancement or to comment on the proposal: https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=13454
Those wishing to vote will find a “vote” link near the bottom of the poll page.