Can't really comment without running it myself (,lack of another player precludes that at the moment, but I will say one thing about the Goliath: it has a serious handicap in that it cannot torso twist, but that's slightly alleviated by the fact that it canmove diagonally without facing changes. Sure, it doesn't make up for no torso twist, but used smartly it can be quite a help.
Also to answer a question above, yes, quads can kick directly behind them.
But in the end, I'd still have to give it to the Griffin: its marginal advantage in speed and maneuverability of the JJ, gives it a bit more flexibility than the Goliath possesses. It would take a patient player, but I'd say 2 out of 3 games would go to the Griffin.