IMO, there is no comparison between the two tractors.  I did run a neighbors 8670 one year planting beans.  The super steer was something to be desired, reminded me of a 2+2.  Hydraulics are levers instead of switches, no command arm, etc.  Sure the NH are cheaper to get into, but will also be worth much less in the end.  My custom hay guy just sank over 15K into his 8970 this past summer on the engine and hydraulic leaks.  I currently run an 8XXX series and has been great.  Very tight turning radius, powershift is smooth, command arm hydraulic controls, scv flows and times all within arms reach.  Just my .02!