Smooth edge buckets (like your OEM one) are great for loose material handling. Not so great for digging or breaking up hard pack. The teeth in a tooth bar greatly increases the pressure applied to a much smaller area allowing the bucket to penetrate hard pack. The bucket is pushing against 6 or 7 teeth instead of the entire length of the bucket.I have several areas to grade level and a few with brush and very small saplings. From what you are saying, the Pirahana would be the choice.
Is there any reason to take the thing off? What chores does the OEM edge perform better?