Wiring, foil or mesh shield ?

Is there any appreciable difference between foil and mesh shield.

I can find plenty of cheap shielded cable for Nav lights that use foil shield material. Thinking of using normal PVC instead of Tefzel, the wire is running in a plastic conduit anyway, so the fire advantage of Tefzel are overriden by the conduit material.

Thoughts ?

I'm no expert but I think the tefzel is to prevent heat inside the wire from igniting the insulation, not to protect the conductor from outside flames.

Actually one of the main concerns for Teflon insulation is that it puts off toxic fumes when burned.

Yes, and it burns just fine....it just doesn't support combustion after the heat source is removed.