Here you go, Piston area and force.

Well, I don't have any skin in this, but I deal with high pressure pumps daily, and I can assure you the greater area increases the force on the bearing. That is why we have to decrease piston size for higher output pressures. To save the bearings. The best way I describe this to people is PSI. Pounds Per Square Inch. More inches = more pressure / force against the bearing.