I ran a set of ST's on my '07 Ram. They were decent tires, performed well on the road in the rain, handled off-road chores well. Having said that....
I've tried a fairly wide variety of tires on 5 different 4wd trucks over the years. I remember when the 3/4 mudder (Cooper ST's, Mickey Thompson ATZ's, Dick Cepeck Fun Country's, etc) first began to come on the scene. Finally there was a better choice than the BF Goodrich AT's and the milder AT's that dominated the market! A tire with the traction of an MT and the noise characteristics of an AT.
My opinion has changed somewhat because, in my testing I've been a little disappointed with the 3/4 mudders in general. Instead of MT traction with AT noise, as a group I find they are closer to AT traction with MT noise. Advances in MT tire technology have made some of the newer MT tires very capable on the highway and surprisingly quiet. My Mickey Thompson MTZ's are great examples of this new breed of MT ( though certainly there are a lot of good MT's with similar performance).
The AT's I have been happiest with have been the Bridgestone Revo's. I never tried the Cooper At3's - But I wouldn't be surprised if they are similar: noise characteristics barely any louder than street tire, surprisingly good off road traction, outstanding foul weather road performance.
The 3/4 style mudders just never have delivered on the promise for me - traction really not much better in sloppy conditions than the Revo's, and a LOT of extra noise. I would advise you to carefully consider your wants and needs. If you would prefer a more aggressive tire, buy an MT. If you want less aggressive then get the benefits of the better AT's.
David