I have used conversations (and derivatives), gajim, dino, converse.js, and movim to have omemo encrypted xmpp conversations; and I talk to people on Siskin and have used profanity in the past. Seems to work properly, unless I'm missing something.
Before XEP-0459, every client implement their own subset of standard and seldom talks with clients that implement a differnt subset.
Now try to make a voice and/or video call.
Does any Matrix client support voice/video calls other than Element (including Hydrogen as it shares Element Web's codebase)?