The only problem with shooting for the bottom goal is that you have a limited ammount of frisbees to score in a match. There are only 51 ish per team plus the ones on the field at the start, that is not a lot of attempts to get a high score, and if you take all of your 45 and score one than the other team only has to score 1/3 or 1/2 of that to tie you.
*edit*
Tonight we built a prototype shooter and had fantastic results!
http://www.youtube.com/watch?v=LD9Ic_rBRmk
Theres a video