If your bow is as quick as you say, there is no reason to have a 10 yd pin, just use your 20 for anything closer. Your broadheads may or may not fly differently than your practice tips. You definitley want to find out.
"i hear alot of people say not to shoot them into a target"
I disagree with them. When you buy your broadheads mark one and use it as a sacrificial head. They make targets for broadheads, they work great. If they do shoot different you can: Tune your bow, move your sights or try a mechanical head.