Every option has strengths and weaknesses. I have never touched Rocket Chat, but the following review suggests to me that it takes more work and babysitting. Here are two excerpts:
"
Rocket.chat. It's feature set also rivals Slack, it's good looking enough. But, it's made in Meteor. Now, I don't have anything against Meteor and I really think a Slack-clone is exactly the kind of use case where you could use Meteor to its full potential.
Technically I really think it's a downside to be forced to use Mongodb (Meteor requires Mongo). For small installations I really prefer to have PostgreSQL. MongoDB is competent, but for medium to big installations, and I will show you why below.
I strongly dislike the
culture of writing software without minimal care such as having a reasonably complete test suite. You browse through the many packages that comprise Rocket.chat and several of them have no tests whatsoever. Some packages do have jasmine tests, but the majority is lacking."
A second quote, "So, the code itself is not so pretty, you have to keep this in mind. I'd much rather use Mattermost (which is much better structured and with enough tests), but it's not entirely free, so it's not an option to me. For my scenario, I'd rather have sloppy code (that minimally "works") that I can tweak than code I can't see, for this particular venture."
Keep in mind, you could pack everything I know about actually running and maintaining rocket chat in a thimble. But it does look like it's a lot more "hands on." I wouldn't want to take on any extra work, we have a lot on our plate already.
Here's the source of that review:
http://www.akitaonrails.com/2016/08/09/moving-away-from-slack-into-rocket-chat-good-enough
It's not like we don't have the money....BOOM just punched through 400!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!