Discord has been used by MILLIONS of gammers world wise. It's trusted by several big name companys and gamers that should be all the real proof you need... it is even backed and joined by Skype, Which is another MASSIVE world wide chat system/company.

You also do not have to download Discord since it does have a web browser version. As Mythos Said, many gamers use the server as a source of communication.

is it encrypted and how does that effect game play on a non ecrypted server

Makes me wonder what in the world you're hiding so much that you're so adamant about encryption and security on a private server for multiple posts that even chatting on discord has to be part of it *amused*

It's basically just some chat place. If you dont want to share any sort of info, then dont. Not many people on there anyway, at max around 13 at a time, from iris. =)