I always hate agreeing with the inmates over at the Beacon. Never know if my iron grip on reality is slipping out of it's velvet glove or if they are just good examples of the broken clock theory. I have learned to take their numbers with a grain of salt but regardless of any exact number, the Cincinnati mayoral primary is a stupid idea. Primaries make some sense, especially with the 2 party presidential races in the US. You are dealing with people and communities and industries and even cultures that can be very different from Rhode Island to Hawaii or from Alaska to Missouri. Many people in the US will never see or know anything about vast regions of the country.
In a city the geographic size of Cincinnati and with it's population of less that 400,000 and with the non-partisan nature of the mayoracy, the primary is pointless and wasteful both in time and money.
I doubt the cost of campaigning is much different.
I guess there might be something to say for the mayor's getting a larger number of votes through a 2 way race, thus giving the elected mayor a little more legitimacy, but it is just not necessary.