Tire review after a few weeks: They do better out on the wooded hillsides than anything else I've tried. Think loose rocks on soft soil under a thick layer of dead leaves, going up slopes that challenge the wheel motors and sometimes win. They leave more visible tracks on the lawn than any other tires I've tried, likely because of the sharply squared-off shoulders, and they definitely tear up the ground in the woods.
They also ride like a freakin' buckboard. They are 4 ply, but they are stiffer than some 6 plies I've had, and the spacing of the lugs is wide enough that I sometimes feel each lug jolting me a little. I'm OK with the rough ride, because they have been getting me up to some really good dead firewood trees. When mowing season comes around again, I'll use another set of wheels with turf tires and a softer ride.
For those with larger budgets, I would bet that the Firestones would be even better at climbing my slopes, but for the money I like these. It will be interesting to see how they wear and how the traction changes as the corners and edges wear down.