The only possible functional advantage of forged over stamped is the thicker forged could possibly assist in axle alignment.
Curiosity got the best of me, so I broke out the vernier caliper and started measuring. The stamped Campy Gran sport was 5mm thick throughout, faces, tabs, hanger and all. Surprisingly, the Campy Pista dropout was only 5.5mm thick, and the tab ends taper down to 4mm. The Campy 1010A was 5mm thick at the tabs, 7mm (!) thick at the faces, and 6mm thick at the mounting hole on the hanger.
Even at 5mm thick at the hanger, the Gran Sport would still have 5 threads of engagement for the derailleur mounting bolt.