It's difficult to compare yield between the two RM groups.  All depends on when and if we get rain, but somewhere between 40 bu. more and 40 bu. less. In general and would say the longer season hybrids are 15bu better if we get another rain.  We tend to look for 110+ hybrids that pollinate early for their RM.  That being said the best corn we have ever raised, whole field average, was DKC 48-53 @ 145bu/A.  Not real impressive for most places, but pretty good for our soils and enviroment. 

 DKC 48-52 was the refuge/base hybrid.