After much head scratching I managed to solve a long standing issue I was experiencing with C4D and it's displacement channel.
Basically if you use a displacement channel and alpha channel in one texture; in order to stop the alpha conflicting or stopping the displacement you must not use black - 50% grey is king. I basically used the same displacement map for the alpha (.psd) which had 50% grey as its background and white for positive displacement; the alpha channel then uses no sampling or any invert/soft etc functions selected.
Posted a gallery image of two Ulster Bank contactless cards which use a displacement map for the 'embossed' card details and an alpha channel allowing the chrome texture underneath to be 'mapped' onto the displacement - effectively giving it that punched through look - it's very subtle but works.
Lighting is key and I'm sure this could have been done better but used an HDRI plus a couple of soft boxes from GSG with Physical render settings from the HDRI kit plus AO on.