Enable PBR and sett glossiness to a very low value, or 0. If you're using the roughness model, set it to something very high

You can already do this, just make a Texture node and plug in one of its channels into the metalness slot

Ah, answered via mail, which was only showing his reply. Sorry

I'm afraid you're using a way too old and unsupported version of SF, you'll have to to update

Possibly at some point, but I'm currently swamped in work on another project I'm afraid :(

What version of SF is that?

There's a longstanding issue of vertex offset and clipping needing custom depth rendering for post effects.

It can sometimes be fixed using specific naming and node setups though, as per this comment: http://shaderforge.userecho.com/topics/693-alpha-clip/#comment-2666

Yep, glad it worked out!

You'll have to show an example, it works for all I know. It seems more likely that you're feeding it incorrect data

I'm pretty sure that this was because the step function was actually more expensive on some platforms, creating a branch regardless. It's possible that it's slower in general though.