The mind boggles.
We now have airplanes flying over Jacobs Field exhorting people not to sign petitions. In the home of the City Club, this is civic debate?
Perhaps we can bring a little market reality to the situation. From this perspective, the petitioners seem, well, rational and responsible... guardians of the public purse.
Let's look to Pittsburgh to see why.
Here's what an economic development analysis for a convention center looks like. Prepared by Carnegie Mellon, the analysis looks at the benefits and costs of building the new convention center in Pittsburgh. Download the PowerPoint [1].
The conclusion: the costs outweigh the benefits. Pittsburgh went ahead and built the center anyway. And now the folks in Pittsburgh have got a beautiful big box. They are not meeting their attendance projections (but, then again, neither are Baltimore or Washington). No meeting of minds at Downtown convention center [2]
Maybe the petitioners are right to slow things down, get a plan in place, then focus on figuring out how to finance it. (Those are the rational steps Portland, OR is taking with its center, as this flow chart shows [3].)
A chart from Jacksonville's recent market analysis shows the problem: convention space is outstripping demand. It will likely take some years for the market to rebalance. 
We all want Cleveland to succeed. However, a convention center is placing a very big bet on a very soft market. The medical mart might be able to mitigate this risk by providing a base load of demand.
The whole equation needs a sharp pencil, though. We have yet to see a plan. (In the face of perilous market conditions, how will this whole project work? The County's grades for managing capital projects are not all that high, according to Governing magazine. Learn more [4].)
Years ago, Richard Shatten cautioned Cleveland's leaders against simplistic strategies to complex challenges. Read more [5].
In the end, we all must face a cold reality: markets don't lie.