I think it's important to have the teeth below the bucket because it normally adds strength to the cutting edge of the bucket and keeps individual teeth from twisting, particularly when you are using the teeth to scarify while going in reverse. However, your ability to backdrag nicely or spread materials evenly with the bucket lip is about completely destroyed with either type of teeth. Your options are to buy a second bucket without a toothbar (what I did since my loader is quick-tach) or take the toothbar off.
Don't get me wrong. I LOVE my toothbar. It's like fingers on a hand. Can you imagine using your hand with no fingers? I can rotate my bucket down or up so I can see the teeth and use them for all kinds of fine manipulation of anythings from stones to limbs. I can also say that completely smooth backdragging is possible with the heal of the bucket, but perfect backdragging is way overrated. I can't think of much where a few lines from toothbar teeth really matters.