Just to throw my 2 cents in. Howard Efner did some development testing, and we found that HP5 developed in D-19 was a very good combination for Platinum/Palladium.

The negatives printed just a little muddy in pure palladium, but with the addition of 1 drop of 5% and 1 drop of 2.5% Sodium Platinum (Na2), the images were absolutely stunning. We didn't test FP4, but I suspect the results would be similar.