The class eleven John Deere X9 and the class 9 Claas 8700 were ran at farm progress show.  They both had 16 row corn head except the Claas had the chopping feature. Even with the hp requirements of the chopping head the Claas matched the deere for production rates. In doing so it also had HALF the loss and the grain quality was better.  

The claas has 10% more thrashing and 15% more sieve area along with thrashing and separation being able to adjust independently.   that was a big help in matching production rates and a cleaner sample with less loss.