In doing research today I see some valid reasons for not going XMPP. The question that raises for me is merely: How do these things interoperate going forward? I'm through with walled gardens, particularly with something as important as team communications. If not XMPP, then what needs to happen to allow any chat to federate with any other chat? And, perhaps equally important, how does one move data from one to another. Data lock-in should be on everyone's mind, but it always seems to be an afterthought (so far after that it doesn't come up until the disastrous occurs and your vendor sells out and closes up shop, or becomes like SourceForge and destroys user trust).

I don't mean to rant at you, of course. Mattermost looks great and it is open source, which means any complaints I have, I am free to put my money/time where my mouth is and fix it.