You can't be bumped out of your seats as long as you give the minimum donation.
Its kind of a crappy system though. I really don't have much incentive to up my donation cause my seats won't likely get better. As of right now I have 4 tickets on the goal line about 20 rows up. I could give an additional $1000 and not be guaranteed any better seats next season.
I know it would be too difficult to re-seat the place every year, but that would definitely generate more money. I'd scrape together as much as I could to have a seat 40 rows up and between the 30's.