Um, DE cold one knights are WAY better than lizard COR.
They're S4, with automatic lances for free, meaning they hit at S6 (two higher than us). They have I6 and ASF, so they always attack first and reroll their misses. They also reroll 1s to wound, and they wound everything on 1s because of S6. They average more wounds than COR do, they're better against armor and high toughness than COR are, and they get to go first so they don't die before making their attacks. Plus, they can take magic banners and weapons!
Predatory Fighter is a drawback, not an advantage. The only thing our COR have over them is that they're coldblooded, and even that is mitigated by the fact that the DE version have higher leadership anyways.