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.