The thing is, there's Akamai and Runonflux, two companies hosting the entire public SimpleX infrastructure. If you're not using Tor and SimpleX Onion Services with your buddies, these two companies can perform end-to-end correlation attacks to spy on which IPs are conversing, and TelCos know which IPs belong to which customers at any given time. Mandatory data retention laws about the assigned IPs aren't rare.
Yes, that's why I said I don't like their relays. It doesn't even have to be Akamai, you need to trust SimpleX first that not to track your IP. I'd rather use a messenger where something is not possible (or even hard) than trust.
As long as IP leaks are possible, I'd rather also use Signal, where at least the rest is battle tested and state of the art.
My concern with Signal is they'll either comply or move out of the EU with the incoming Chat Control, and I'd rather have a fully decentralized messenger with as few leaks as possible.
I liked the SimpleX concept, but would prefer its relay server were replaced by Tor or i2p network.
And if they used Signal instead of NIH protocol.
Actually, the only unique SimpleX feature I really like is that it uses separate ids for every connection and group.