Wire is still improving quickly and it looks very promising, but this (https://motherboard.vice.com/en_us/article/secure-messaging-...) is reason enough for me to avoid them for now. Signal is still the best secure messenger in my opinion.

Indeed. There is no reason to store that what so ever. Idealy, messaging is fully distributed, secure, and anonymous.

It wasn't entirely open sourced last time I researched it, which is one of the reasons I switched to Riot.

My understanding is that the client code and some of the server code is on github, and the rest of the server side code is being released gradually:

https://github.com/wireapp

https://medium.com/@wireapp/open-sourcing-wire-server-code-e...

https://medium.com/@wireapp