I still self host my TS3 for my nerd herd, and as an EvE online player (currently trying to win, but thats hard), you have to be fluent in all voip solutions as they all have different requirments and say a lot about your group.
Discord - small group, utilizing free services, may have an auth tool, used to keep in contact with people from old groups. Remember kids, if the product is free, you are the product
TS3 - mid-sized group (100-1000 players) requires a real IT team, will have an authentication system and generally will have their shit together. Ease of set up is handy, but admin user accounts can break servers.
Mumble - Welcome to the big leagues. (1K+ players) The resources you require now require resources in meat-space and are rather substantial. You need real IT security and people on a payroll. It will drive your admins nuts for about a week setting everything up, but once its done, you wont have to touch it again.
Serious EVE players are something else. The mention about IT security isn't a hyperbole, some EVE players take the espionage meta-game very seriously, and even though it's not only against the rules but also illegal, that's not gonna stop them. I mean, once they literally got someone to turn off electricity for a whole town just so they can win a fight (I tried to find a link to the article, because I'm 90% sure I did read about it somewhere, but I can't manage to find it anywhere, if anyone has a link. Maybe it was just a rummor, or an unexecuted plan?)
Yah... That used to be me... I try to keep in touch, dip my toe in the pool every year or so, go to the conventions and such. Almost 10 years ago I wrote my alliances auth system in Ruby on Rails, included those identicons you see as the old default profile pictures on github as the avatars on the internal forum and you couldent change then. The reason for this was that the token for the icon was your name and the posters mashed together so if a screenshot leaked we could reverse lookup who said what.
We never actually caught any spies with that, but that was the level of paranoia and planning that went into a crappy mid-sized group, in the game of today there are actual armies of 10k angry nerds. They are much more casual about it though, which is healthier for the players.
There is a difference between having it turn on and hardening it against DDOS attacks while haveing 500 nerds try to use it as coms for massive videogame fights (this has happened, its against the games rules, but it has happened). If you can do that in a day, please empart your wisdom.