1 you do not really need ANY adjustable gears! Some cheap cams come with improperly indexed pin, so they need to be corrected, but that is just another reason to stick to high quality cams!
2. Try wrapping a timing belt around a stock and then Chineese pulleys, you will notice that you will have to force the teeth into the gear after 220* or so (that does not happen with a stock or HKS pulleys). You may say, the actual belt doesn't make a 220* contact with the sprocket (and you would be right), but it shows that they are different! And that mismatch must put more stress on the belt teeth!
If I had to, I would only use pulleys that fit the belt similar to stock pulleys!