The test server is cross-compatible with the live client, but to use some of the new features you will need to switch your client to the beta branch in steam.
Please report any bugs you discover in this thread.
Some taxidermied bodies (e.g. trolls) do not display color if painted, this is due to the new status color system in vanilla and is likely unfixable. Rainbow unicorns now require you to have serverpacks mod installed and working on the client, this is again due to the new status color system.