The source code for this is very old an outdated, there's source which has "ALL" bugs, cheats and exploits all fixed and also from what i was told is that it also includes a DDOS shield for UBER protection.
There are tons of new features to it like the ability to broadcast live radio aka mp3's off of a server instead of them going into the client and all the korean bits working, minus the new Ninja job and skills.
Since when is 3 month old source considered outdated. And I doubt you're right there will never be bug free source code.
There is basically 3 sets of base source code out there. They are the C++ Files, the Plumewind Files and the Official Philli files. Every single set of Mir files have been built around them.
No one ever fixed up the C++ files (Mir2EI) although numerous attempts where made.
The Plumewind files (Aka 1.9) source code was stolen and leaked and where fixed up by numerous Chinese groups and by Nick and Damian over here. They've formed the core of every set of files since be they Hero or otherwise.
The Philli source code while fairly old was only released recently. From what I've seen the Chinese are not interested in this source except to maybe nick some code from it.
I can name every group that physical codes and releases files these days and of them only one is close to what you say and that's UC845 and I can ensure you that they are not bug or exploit free and are based on the LOM2 source you just said was old and outdated. They are currently working on adding the 4th class.
Chinese servers have had the Music system for god knows how long now in different variations such as an NPC Command, Mapinfo ( MUSIC(webaddressofmp3)) and Mapinfo (MP3 name file located client side). It's not a new feature and it ain't a special feature.
Most of this is pointless to us of course since the Chinese pack there files mainly (Including UC845 although there client is easy to unpack)