The first way would be better, since it actually gives the users freedom of choice to have a dynamic or static arena. Not sure if it's what you're looking for, but you can actually demolish your own seats in BB. Not sure how many people know of it, since I believe a lot of users here only joined BB after the courtside seat cap was introduced (I used to have like, 700 I think). Just add a negative in front of the number of seats you want to demolish and you'll be refunded. Then you can construct whatever amount you want in another category.
Hey, cool. I didn't know that.