I have been running a 653 row crop head with Bish adaptor on my N7 in soybeans. I regularly run up to 8 miles per hour without dropping a bean. Above that speed it is difficult to keep the combine on the row although the head still works well. It IS high maintenance. If it is serviced regularly and kept in close adjustment it will work trouble free. If it is not kept in good adjustment it will not work in grassy conditions. Thank goodness for Roundup. I just purchased a 1990 653A head ($4000) because the A series has heavier bearings,supports,and chains(belts) and is easier to service. I have no experience in any crop but soybeans. I love the job it does. Obviously I think it is worth the extra maintenance. I can combine beans as fast as people with much wider heads and still go down the road between farms without dropping off the head. The narrow head is also an advantage in uneven ground of which I have an abundance.