0 ZERO!! I hate multi-ball!! Sorry I couldn't vote because there was no 0!!
I feel that multi-ball really takes away from the true game play as it disrupts your connection with the ONE ball. You create a great flow and control and have full mastery of the ONE ball and then all Hell breaks loose with a bunch of balls going every which way totally out of control. Even the Master Players will trap the extra balls with a flipper and concentrate on just using ONE ball to make the shots. To me multi-ball is not a reward. It is a punishment! Multi-ball just creates a mess in my opinion!!
To be fair though I can tolerate 2 ball multi-ball.