Don't much like the "Additionally, winged gnashers glide silently after prey, then make a swift diving attack."
How's this:
Winged gnashers use tactics much like their land-based brethren, circling around their prey until it is surrounded, and then closing in with surprising speed. Winged gnashers fly quietly when gliding, and they often try to surprise opponents with diving attacks.
Further, winged gnashers are Large sized, so we should modify the sizes of the Pack Overrun attack. Something like:
Pack Overrun (Ex): A pack of four or more winged gnashers may use the overrun attack. The pack overrun prevents a Huge or smaller opponent from avoiding the overrun and does not provoke an attack of opportunity. In addition, if the pack successfully overruns its opponent the pack may immediately end its movement in the opponent's square and pin the opponent. Pinning in subsequent rounds still requires successful opposed grapple checks.
For the overrun attempt and subsequent grapple checks, treat the gnasher pack as a single Huge creature with strength equal to that of the strongest gnasher in the pack (so that the pack cannot overrun creatures larger than Gargantuan). The gnashers' overrun and grapple checks also receive a bonus equal to the number of gnashers in the pack within reach of their target (that is, up to +4 for targets of Medium size or smaller, up to +8 for Large or Huge targets, or up to +12 for Gargantuan targets). Furthermore, any adjacent gnashers can choose to deal damage with their bite attacks during the grapple.
Apart from that I think they're done.
