This is indeed an excellent question and a great opportunity to educate as well, so thank you for bringing this up.

I recall when the Kimoto Gravity Well was first announced and implemented in Megacoin to combat mining pools which were taking advantage of Megacoin’s previously implemented, inadequate difficulty adjustment algorithm. This was a major issue for Megacoin and many other coins at the time, so it was a critical move. CGB on the other hand, since its creation, has employed a linear, rapidly adjusting algorithm (difficulty adjusts every 2 blocks) so the problem has never occurred, nor will it. As a matter of fact, when the Gravity Well first kicked in, I watched the Megacoin blockchain and compared it to the CGB blockchain as the multipools would hit the coins and quickly get bumped due to the difficulty adjustment. My perfunctory observation indicated that not only did CGB’s difficulty adjustment algorithm work as effectively as the Gravity Well; it in fact outperformed the Gravity Well by showing more fluid difficulty adjustments.

Kimoto certainly did an excellent job turning a problem in MEC to a selling point, but for CGB, such a move was never a need and would be pointless.