I would argue that the Cooper ST tread is a mild mud tire, or an aggressive all-terrain, not a mild all-terrain. I'm using my STs as a street/winter tire with much satisfaction. The considerable void with good siping and a very thin tread face in 255/85 help it cut through snow and slush. I agree with you Tim, it's nice to have a street friendly tread on the many road miles we all travel, even just to and from a trail. But in my opinion the ST is a pretty loud tire.
I'm a big fan of the tough, Toyo tires, but just remember that much of that ruggedness is related to the overall stiffness of the tread and casing and the load-range-E Toyo MT & M55 will offer less flex and deformation at a given pressure than a very soft and flexible tire like the Cooper ST. Because of this I can/need to run lower pressures to make the tire ride & deform to my liking. If I like a typical D-range 255/85 @ 15-psi on certain terrain, I prefer it at 10-psi with a Toyo MT E-range.
There is little doubt in my mind that these Toyos are some of the most rugged radial light-truck tires out there. If I was most concerned about getting punctures or tire failures, the Toyo MT (or M55) would be one of my first choices. I don't know if they can take a shot from a .22LR, maybe a glancing blow

. The Toyo MT has a distinct advantage over the M55 with its sidewall lugs. Letting lots of air out does put the sidewall lug on the ground instead of thin, smooth sidewall like on the STs. The MT also has a deeper, more open tread.
If wet/winter traction was a concern I would not hesitate to sipe the Toyo MT.
I'm not an efficiency freak... but I do hate to have MT's of any sort when most of my driving is on highways and fuel cost is something that I'm very conscious of. I like being able to save my horrible gas mileage for the offroad bits of a long road trip.
Anyone ever done a check of rolling resistance for tires? There is the obvious which applies to Mountain Bike tires. More aggressive = more effort to move them. Less aggressive = less effort to roll, and in some conditions less grip of course.
I sure wish I could find that $116 price on Cooper ST's I found way back. That would be a great tire for a long road trip of mixed off and offroad driving. The only problem is that I don't think those are up to day in and day out of aired down wheeling on these sharp rocks in AZ. (which is what my current days entail) My old ones got really beat up really fast.
Agree 100% but it's just difficult to make the trade off. With rare exceptions like the Cooper ST and BFG Commercial Traction (and maybe the BFG AT?) choosing a tire that does off-highway and on-highway very well is tough. And only one of these three comes in a 255/85. Considering the new BFG MT KM2 seems logical, it's also an load-range-E tire now like the Toyos, I have read it's quieter than the older tread KM. Some people love the BFGs but I have read plenty complain about poor balancing.
When it comes to pricing I think the Cooper STs were a screaming deal, just last year I paid about 137.00 per tire, but tires have gone up and I don't expect to buy many tires for less than $200.00 each for a long time.
My memory has faded but both the Toyo M55 and Cooper ST make noise. The STs are probably louder, but more than anything they have a different tone. The Cooper ST has a more traditional mud tire hum while the M55 has a higher pitched whine like a semi-truck highway tire.