Fast Iteration Mode

Hey Folks,

I just read the article about the fast iteration mode. I am not a 100% sure if I got everything right out of this article.
So the main point is that small projects will generate faster, as long as there are no dependencies to the engine itself?
We got a project with about 20 -30 classes and did never change anything at the engine.
This is how our Build.cs File looks like:

PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "UMG", "FMODStudio" });

// Uncomment if you are using Slate UI
PrivateDependencyModuleNames.AddRange(new string[] { "Slate", "SlateCore" });

Is it safe for us to activate the Fast Iteration mode?
If I change my BuildConfiguration.xml the following way:

    <bUseUnityBuild>true</bUseUnityBuild>
	<MinFilesUsingPrecompiledHeader>6</MinFilesUsingPrecompiledHeader>

I can’t compile any more. Unfortunately I can’t find any more in depth docu about this. Could anyone explain a little more about what this is doing?

Cheers