Another thing is lighting, the fine cross-hairs can disappear in low light scenario's while the post and cross-hairs will still stand out. What is good for target shooting might not be so good for hunting.
Depends on how you use them, but a fourth line, especially the overhead wire makes it a lot more likely you can see enough to make the shot. The bottom post, wire, bead, whatever, is the most likely to be invisible in poor light. That's why I like four. One truly only needs to see one segment of horizontal and one of vertical. The rest are a luxury.