I ran my 8820 to 3500 motor and now have 3200 motor on a 9500. I replaced a lot more tin and little stuff on the 8820. I feel that the 9000 series are simpler and better to work on. less belts and chains. Quieter, easier service, motor compartment stays clean, more comfortable to run long hours in. I was nervous about all the electronics and hydraulics on the 9500, but I never had a breakdown, just normal maintainance.