IIRC the SAT is tube type while the SAT II is tubeless. So while the SAT II is $280 cheaper is also does not require a tube. I have had both and the choice really depends on application.
The SAT II will outpull/maneuver the SAT on ice/snow/hard packed ground. The narrower lug of the SAT II bites better on hard surfaces than the SAT. For a yard tractor the SAT II is a great tire; the SAT shines in soft field conditions for heavy draft like plowing. I have not chained up my 3020 loader tractor since installing the SAT IIs. | 
Super all traction vs. SAT II
