I'll try to answer Tig's question, though no white paper here either. I'm going to answer it subjectively, because that's how I am! :ernae:
Active Sky has always produced a much more believable environment than default weather. It has improved drastically from ASX to ASE. There are times when I am flying with ASE enabled and it looks exactly as it does outside my house. Meanwhile default weather produces results like it is on the other side of the world.
When it comes to storm systems, it still isn't exact like you might see on a real life radar, however if in real life the station is reporting thunderstorms, you'll most likely see thunderstorms. I've found the weather in ASE to be more accurate and more realistic than previous versions, and a million times better than default. Since switching to ASE, I've not been hit by any of those nasty wind shifts either. I find that the updrafts and turbulence feel much more realistic with the latest version too. That being said, I still have
wake turbulence turned off because it is incredibly annoying in multiplayer.
Visually, it changes the way fog and visibility works (vs. default), making it look a whole lot better than the weird blanket effect that default FSX produces. I love the way it makes the sky and ground kind of blur together like it looks in real life, especially on hazy days.
I also have REX 2.0 but never use the weather options because it revolves around a flightplan. Active Sky lets you fly anywhere you want and it constantly updates without interrupting your FS. (though it does give you a jolt when it first initializes) Performance wise, ASE is better on FPS on my end than ASX was.
ASE weather and REX textures produce an environment second to none in FSX. Active Sky is like Track IR these days. If I don't have it or it isn't working, I won't fly. That's my non-white book, quick overview of ASE.
