I'd have to agree with Brett in terms of a business case. I read the article he posted and while I don't agree with all of it, I don't think there is a business case to be made for a stadium in a business sense.
That being said, I agree with him that a stadium is one of those quality of life pieces of infrastructure (kind of like the oval or the 4 pad arena) where you pay the money to build it and realize it might make some money back, but never enough to pay for itself. That's just the nature of some things that make a city great.
Where I don't agree with Humphrey's is on the economic impacts of a sports team and stadium. I preface this comment with i'm not an economist, but I'm looking at it from a common sense view. I'm also going to use Shannon Park for my example.
When I look at SP - I see that there would be room left over (after the stadium, road improvements and parking lots) to probably still include some mixed use development (hotels, apartments, restaurants). So, to me there is an economic impact of building the stadium - create development opportunities around it.
Plus I look at the stadium as much more than just a football or soccer game opportunity. The Stampeder's did 9 home games for the 2010 season, but this stadium could also hold soccer games/tournaments and concerts. So all these people assuming it would sit empty seem to miss those things too, which is where I find Humphrey's article lacking. It didn't seem to take that into account, just the pro sports teams. But with even 9 home games, depending on how well tickets sell and the size of the stadium - it could generate impressive tourism draw. What was the 'announced' economic impact of Touchdown Atlantic - something like $4 million for 20,000 people at the game? Aren't we talking about a stadium somewhere between 20,000 and 50,000 (for a grey cup)? If you look at the top end size #, the economic impact in HRM could easily be double the $4 in Moncton per game (40,000 seats, 2X the economic impact). Now, I'm making a huge assumption there.
Plus, I suspect that if a team landed in Halifax you would have a huge draw all over the maritimes, especially if the team reduced the games in Halifax to say 7 and did 2 in Moncton. Add to that people taking the train, flying, driving, staying in hotels - this is where I doubt Humphrey's article from a common sense perspective - and this is all with a football team. Add in soccer tournaments and concerts and I see way more potential. That's just my rant on it though.