I do not know much about the Bighorn. I am very familiar with the SXT. It is a very very good all around tire. Good tire for travel on packed snow and ice. Descent tire out in the hills, and good mileage out of it. The only area where I wish it was better was when the snow gets knee deep ;-) I am willing to bet SXT is the more popular out of the 2. I know I love the SXT, and I will be getting another set of SXT's sometime in the coming weeks.
Like you,I do prefer a 10 ply tire. If you get a flat with your 10 ply, you would of just ruined your 6 ply tire. A 6 ply will ride a little better, but I am willing to sacrifice a little ride for never having to break out my jack.
Les Schwab is all about service. Take advantage of that free rotation, and keep these or any other tire you purchase rotated. I see a lot of people preach 5000 miles before you rotate, but thats about 2000-2500 miles over due for me. It does and will make a difference in the mileage you get out your set a tires.
