It seems like at each major marathon we hear about wild fluctuations in pace. Wild surges, and changes in pace and all of a sudden 2:08 runners produce 2:12 times.
It seems to me that top runners would be better off running a even pace for 35k then racing the last 7.2k to the finish. Brian Sell does this type of race and has been very consistent and effective.
Do several longer runs (21k to 30k) in your training at MP race pace to get yourself very familiar with the goal pace and then on race day, simply do the same thing but for an extended period. Cerntainly on simple to execute but it will produce a better end time then the wild flucuations in pace seen in top marathons today.