The update for 2.1 is definitely not stable or long term playable right now. We're still playing on the 2.0 version (RP 1.6.13) on the server, the new update is experimental so we can get an idea of how and when we could migrate our world safely.
If you want a version for a long term play though I can recommend either RP 1.6.13 or this server pack Oceanlabs 1.0.5 (both on Factorio 2.0), it's working well and with minor issues has full progression through all chapters.
RP 2.0.0 on the other hand needs some more time to cook. Our first test run with Oceanlabs 1.1.1 ended after 2-3 hours with the conclusion that we will stick to the older version for a bit longer.