There is no questioning the fact that Delta 100 is sharper than PXP. It's simply better, period.(posted 8369 days ago)But if you have 100 rolls of PXP and you are looking for more sharpness, I suggest you try a high acutance developer. My first recommendation would be PMK. PXP in PMK is a great fit. You'll get maximum sharpness and wonderful tonality. PMK is available from the Photographer's Formulary.
If you want a more readily available developer, you can try Edwald Fg7 or Agfa Rodinal. Both would show an inprovement in sharpness over ID-11/D76.