It works. And it works really well. But it works when you add the enzyme before you pitch the yeast. But the real issue is how important to you is the clarity of the wine you make. If it's not important then skip the enzyme. If it IS important but you are skeptical of how effective the enzyme is why not prepare 2 one gallon buckets of a fruit juice - mango, pineapple, apple, berries. Add the enzyme to one bucket and none to the second the ferment both using an identical protocol and when you are ready to bottle compare each for clarity.