The enhancement itself is far more potent when in 4-legged stance, so after using it, it is best to switch to 4-legged stance as soon as possible.
The Counterstance effect from Cacophony stacks with the JA Counterstance for increased counter rate. The defense penalties are not cumulative.
With this buff, it is very effective to pull many enemies at once and stand in a position where you can counter them all (Gnole's autoattack and counter area is wider than players: he can attack enemies in his peripheral vision even when he isn't directly facing them). When doing this in 4-legged stance, by the time one enemy dies, many in the group will be severely wounded just by the constant counters.