the gt's are new for '16. so as of yet are unproven in the field.   but they been developing it for four years.  rode in a combine last fall that had a gt twin chop head on it. was hard to find a reason to hate it.   they were harvesting a field of highly variable corn( gravel pit, to the heaviest ground we have locally) in the same round.  can't say much about the I's and II's.