This article on XDA-Developers focusses on encryption features of Conversations and an interview with developer Daniel Gultsch. Nice read!
Q: What motivated you to develop Conversations?
A: I am using Jabber/XMPP for many many years. Even back in 2009 I was able to use Jabber on my Nokia e71. Sometime around the year 2012 I switched to an Android phone, so I suddenly was unable to use Jabber. [...]
Q: Can you give three reasons why Conversations protects your privacy better than Whatsapp or Threema?
A: I don’t have to give my private phone number to strangers if I want to chat with them. I could have a private and a business account. I can disable the business account after my shift, to prevent my boss from annoying me during my free time. WhatsApp allows everybody to analyze my app usage patterns any time. (My boss could stalk me to investigate if I am using WhatsApp during my working hours or if I am using WhatsApp at night instead of sleeping and coming well rested to the office.) This is different with Conversations; Conversations also doesn’t upload my entire address book to Facebook.
Q: Is it allowed to compile Conversations on your own from your Github and use it for private use?
A: Of course. Not only private, also for business and everything else you want. It is also allowed to modify the code to meet individual requirements.