I really like my Druatracs on road and off in all seasons and conditions. However, being a winter rated tire the compound is soft and if you are heavy on the pedal in hot climates you may wear them down pretty quick. Considering the sides are two-ply another downside to the soft compound is the sidewalls do nick easily on granite/quartz but nobody in my club, and there's a few of us, have had a Duratrac sidewall blow out on us despite there being visible damage. New, the tread depth is 18/32" and I've averaged about 8,500 miles or so of distance per 1/32 lost.
When I bought my Duratracs, I was looking at STTs as well. The Duratracs won my money based on price. I am happy with the decision as they've taken my family through some nasty rain, sleet, ice, and snow storms with no loss in confidence on their adhesion to the road.
The other day I ran into a Durango driver who also had Duratracs so I asked him what he thought. He said they were OK but he preferred his old MT Baja MTZs on ice. That being said, if you run two sets of tires the Duratracs can be studded, not sure if the STTs can and depending on the conditions you use them in, that could be a deciding factor.