Several Fellows suggested Slack and other platforms to AFLI as an alternative to Workplace. 

Kudos to Slack, but Workplace offers an instantly-familiar interface, as most people have used Facebook. It therefore has little to no learning curve for adoption, along with a mature mobile-phone based app. The same is true for other platforms like Basecamp, Ning, etc. where Fellows will be greeted with a familiar environment that is easy to use. Workplace also works great for both small and huge teams or in instances where communicating is difficult.

Lastly, Workplace is free to organisations like AFLI which ensures cost doesn't become a limiting factor as the Fellowship grows or in the event AFLI takes on new projects that attract a large user base.