I had a lot of experience on all terrains with the KO2s on the 80. The only time I really had any trouble was snow deep enough to give nearly any tire, especially All Terrain tires, trouble.
I do not have the same experience yet with the ATx. I notice the road noise more but that's probably b/c I'm driving a 2007 instead of a 1997 but it's not enough to bother me. The tires weigh about the same and look very similar. I do prefer the look of the KO2s better but I couldn't argue since I got the ATx at 50% list price. I was trying to decide between Grabber X3 and ATx. Maybe when the ATx wears out I'll try the X3.
So in a round about way to answer your question... the jury is still out. Thus far, the ATx has been able to do everything the KO2 has - and at a higher pressure - since I can't air them down to 8 like I could with the KO2s on the 16" OEM wheels. On my OEM 18s, the lowest I've gone is 15.