The cab is better on the 9790. I prefer the Sisu engine over the Cummins. Have to go to Cummins dealer for repairs and they (local Cummins dealer) never acted interested in service. Also I think the final drives are heavier built on the 9790. As to trade difference a CaseIH salesman told me he looks on Fastline and Tractorhouse websites, throws out the high and low asking price, averages the rest and arrives at a value.