I believe that with the smallest metro market, a AAA team in Madison is too close. Brewers need to be a statewide team. I'm not sure how much of their business comes from Madison and SW Wisconsin, but it can't be insignificant. Some people would probably skip the drive to MKE if there was a AAA team here.
I don't include myself in that group. I live in Madison, and I don't think I would attend a Madison Brewers game instead of driving to Milwaukee. I haven't been to a Mallards game in over 10 years, because the novelty wore off. I like that I can see baseball at the highest level in a relatively easy fashion.
I would be curious to see how the markets with a AAA team close to the big-league club have their attendance affected. St. Paul/Minneapolis, Seattle/Tacoma, Detroit/Toledo, for example.