Yeah, if you're concerned with overclocking performance, then you should stay away from generic ones.
Also, FC-PGA chips can exist as both a Socket370 format or Slot-1 format. An FC-PGA Socket370 chip requires special Slotkets though, and older PPGA Slotkets won't work. There are Slotkets that work for both chips though, AFAIK most newer decent slotkets work for both types.