You'll never find a stable source, atleast not for free. The people who make the stable ones aren't about to release them, would lower the attention their's get. You really have 2 options, fix the issues in a current source that's been released (which is an extreme pain in the ass). Or make your own source (which is also a pain in the ass until you learn enough).
If anything though, I'd say check out the Shadow CO source. It's what I'm learning from, mind you, there is a lot of bad code in it, and if you don't pay attention, all it takes is one person to completely destroy your database, lol. But I won't say how.
I've made a few fixes to mine, so server crashes really aren't a major thing now, however, I don't think I've had over 20 people on at once. It's not exactly open to everyone, just a few friends, and their friends, mainly to help tell me things wrong in the game. In time, once I've added all I need to add, I'll get more people, and fix lag/crash/freeze issues that come afterwards.