That's it.

I don't recommend doing this as you're paying a heavy price for refraction

This is a known issue, and yes, most likely it's the GGX that is missing. Not sure when this will be fixed I'm afraid! After GDC at the very earliest

The directional LM issue is likely a lot more involved than the opacity clip one. Opacity clip is likely a one-line fix, while the directional LM requires a lot of restructuring. The reason for this is that you need to run the BRDF twice, which the SF compiler is definitely not designed for.

I'll look into this first thing when I get back to updating SF. (Considering getting someone to help maintain SF, as I'm getting more and more busy with another project at the moment :( )

Odd, not sure what could be causing that. Different quality settings? Different Unity versions?

Why is the render order & type opaque? Try transparent

My fault for not doing what exactly?

There is a forum, It's right here: http://neatcorporation.com/forums/

What would it print and where?

It's not really possible since it's all done on the GPU I'm afraid

I think you'll have to compare it to the code in Unity's shader in this case, to see what's different. Not sure what to do otherwise