You'd probably see a very odd scatter-plot of results. Take the courthouse marriage (no-cost option), that can either be the couple where neither one of them gives a fuck about money and will be perfectly happy the rest of their lives, or you have the trailer-trash couple doing the shotgun-wedding thing that will be done in two years. I think you'd also see things skewed on the uber-expensive end of things by celebrities who treat marriages more like saying they are "going steady" rather than an actual life-long commitment.
I would be more curious to see the statistics on how long a marriage lasts when the couple lived together for a significant period of time before getting married.