I am not a PML expert and probably never be, but I have worked with many good PML experts on real projects.
NeilD has over 1000 posts on this forum, and I have seen many of his posts in the PML and the draft section.
I have not worked with NeilD nor known him personally, but I would recommend him based on his contributions to this forum.
There are a couple more Neils on this forum who are experts in PML, but I think they both are busy working in Cambridge to bring us the improved PDMS12.