Hi Deri, thank you for the swift and helpful response.
I'm happy to confirm that using -P-pa4l works for me too and am glad that there is more parity between the groff and device paper format since groff 1.23 as I found the the options -dpaper=a4l -P-pa4 -P-l somewhat cumbersome and being able to use a4l for both is very convenient. Looking forward to seeing further improvements the deri-gropdf-ng branch brings once it's merged. If I can help with the -P-l investigation or testing the deri-gropdf-ng branch please let me know. Best Alexis