9760 or 9770?

Looking to upgrade from our 01 9750 to a 9760. We have been looking at 06 and 07's with 400-700sep hours. Our 9750 only has 1100sep hours so we want a pretty low houred machine. I think I understand all the upgrades from a 50 series to a late model 60. My question is that the 60's we are looking at are within 20-25K of a 70 series (9770), so should we go ahead and spend the extra and shoot for a 70 series? What are the upgrades we would be gaining from a late model 60 series to a 70 series? We grow corn/soybeans with a little wheat each year.