I'm going to be running the L5R RPG soon (again), while I wait to hear if FFG's going to release a 5th Edition.
One thing I might be doing with this edition is drawing it closer to Japan - focussing more on Shintoism, and making 'evil' be a human thing and less of a supernatural force. What does this mean for the Shadowlands? It's an imbalance, the creatures of the Shadowlands act like they do, because they're acting according to their nature - not because they're evil. I know Rokugan was built by blending a lot of legends, not just Japanese ones, but I think, for a samurai game, I want to focus more on the concept of bushido, the balance of nature, and the precepts of Shintoism.
This means, probably, I'm going to completely remove the Taint as an active, evil, corrupting force. Instead, it is a risk you get from performing unclean acts in a region which is tainted by the Shadowlands. If you go into the Shadowlands, and you act with virtue and purity, the taint can't touch you.
We'll see.