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That's a good question. It may be that there's something with the light nodes, that makes things multi-pass instead of single-pass, causing more light to hit it
This is expected, because you've probably misunderstood how the custom lighting input works :)

Custom lighting is rendered additively *per light source*.
Two directional lights * 0.5 = 1, hence it's white.

If you want it to become gray instead of being lit, with the Lerper slider:

That's very strange. There are some platform specific annoying quirks at the moment, and the vertex color name issue is one, but SF shouldn't be empty after reopening.
Did you get any errors in the console when reopening the shader?
Not really, if you enable deferred in the shader, it will support both deferred and forward, and things should work as expected :)
Well, your shader doesn't have deferred support, it's set to forward, things like this can happen when you do that
It's now no longer using a Resources folder, as of Beta 0.36 :)
They can't really work at the same time. The nice thing with having it in mouse mode, is that you can move around the mouse to place the node elsewhere, without affecting which is the currently selected node in the list. This feature would have to be removed if they would both be enabled at the same time. I guess the alternative is to have the hybrid method as a separate option, if you don't care much about being able to move the cursor while picking.
Make sure you don't check the perturbed checkbox, and it should work as expected:
http://acegikmo.com/shaderforge/nodes/?search=Norm...
The reason SM2.0 is under experimental, is because it can break like this. There's no way for me to know beforehand if an error like that is going to get thrown or not. Glad you found out what it was, closing this now :)