Thanks Tom....my question was poorly worded, but was trying to get at the potential for the 'rolling' of hardie siding on 24" vs 16" stud centers.
Even at a smaller portion of the whole cost, 33% more 2x6s adds up.
Perhaps more important is why does Hardie require no sheathing and max 24" centers and someone who apparently has lots of experience advises sheathing and 16" centers??