Ok!
I'm not sure what I did wrong previously but I'm currently running nightly 2014-06-23 and "everything" works:
- Carbons works great, no issues for 48hrs. (it's awesome, a must have for the mobile world of today)
- Jitsi can login
- I got init-script for debian working again
I also found the IM client Conversations for android and it's the best XMPP-client so far! I can really recommend it. Like every other client out there some must-have features are missing: avatars from server and server side bookmarks support.
We'll keep running this nightly until 3.10 is released and report any other issues found.