Nacra 17s definitely had a medal race last year, the results are here: http://mocrresults.ussailing.org/2013/Nacra17/Nacra17.html

If you look at the NOR for the MOCR all of the Olympic classes are scheduled to have a medal race, it doesn't appear any of the classes are trying a different format.

USF18 Eastern Area Rep
Nacra Infusion USA 753