It's not private enough. I am looking for something better than SimpleX. Something that has onion routing backed into it (no way to run without it) while at the same time natively paying for forwarding messages to reduce the likelihood of them selling their user's metadata to be able to sustain their operations.
Discussion
OK sounds good - simplex hosting n client SOCKS5 proxy on .onion is simple
It's not enough to just run over Tor. The SimpleX protocol suggests creating a separate Tor session for each of your contacts. Otherwise the server still knows too much. Just putting them into Tor reduces the metadata, but not by much.
In my version, I want to go further and put each message in a separate Tor route, which is probably too slow. Tor wasn't made for this level of privacy.