Kallithea was an option 2 years ago, now the development of it is basically dead. Rhodecode is still releasing regularly. Just check the feature differences: https://rhodecode.com/blog/133/rhodecode-vs-kallithea-compar...
https://kallithea-scm.org/repos/kallithea/changelog
Now lets look at Rhodecode. https://code.rhodecode.com/rhodecode-enterprise-ce
You will notice that Kallithea has been consistently updated regularly. Besides user like me its also used internally at Unity Engine.
Also the features you mentioned not all are in Rhodecode open source edition.
Can't say for sure but I think Unity's system Ono is using Kallithea as core with additional plugins developed for their own use.
Kallithea is pretty easy to work with and extend. We recently updated and built a CI using buildbot. Rhodecode and Kallithea have diverged enough and are moving differently. Also its a Software freedom conservancy project so it will be supported, hopefully it can attract bit larger community.