some may disa gree with me but this is my thoughts,...low top makes the ball roll earlier, and limits drill options,....higher top weights give the ball more length, and gives more drill options,..low tops for me are anything up to 2.5 ounces,...medium top is 2.5-3.5,..and higher tops are 3.5+,...
again that's just my way of thinking,...I prefer at least 3 ounces in all my stuff before drilling...I wish all balls were 3 top, with 3" pins,...but each to their own...

i don't worry too much about the top weight of the ball---just as long as it's close to 3 oz. i'm more interested in the pin out distance, 3-4".