The difference of the shot would be minimal at most hunting distances. There is a chart you can download to check it for yourself. It is called a "cut-chart archery" Do a google search and you should be able to find it.
The actual difference of shot placement is based on the angle of the shot itself. At the heights you ask about, you are only looking at a 10 to 15 degree angle. This means you would expect the shot at 30 yards to hit where a 29 yard shot should hit. So, you can see it is of little importance.
The only time it really starts to get hairy is 25 - 30 degrees and beyond. The reason for this is that gravity is only working on the "flat/horizontal" portion of your arrow flight. Hold your arrow at an angle and see how it's horizontal presentation (length) changes. The steeper the angle, the less length there is for gravity to work on.
Clear as mud eh? Just trust us when we say that at most hunting (20 - 25 yard) distances, it is of little importance with todays flat shooting bows.