On slick icy roads it is best for the tire to load up with snow. To make it simple, snow sticks to snow rubber doesn't. The reason a tire like the BFG A/t are a good snow tire is because they hold snow in the tread. Look at all winter traction tires they have a tight tread wirth a lot of siping. When your drining around town in the snow look at the tires on the other cars. The ones that look the whitest on the tred are getting the best traction. If you see a truck with big mud tires the tread will much blacker. The siping on any tire specially a mud tire will help hold snow and give the tire more leading edges to get traction. Driving with a mud tire in winter conditions takes some getting use to. I fortunately grew up where we got 30-50 feet of snow a year, so it is second nature. The last year I worked there was January 05 doing snow removal. It was a record Januray getting 25 feet of snow. The short of it is if you want the best traction for on road winter driving get an a/t tire.
Good luck.
Way too general of a statement on MT's vs. AT's. Siping, compound, tread width are all more important than any AT/MT distinction.
My MT's are so good in the snow my wife prefers to drive the 80 on 37's on icy hardpack over our minivan with dedicated snow tires. Different vehicles, obviously, but

is going purely on what feels right to her, and she has had some bad experiences (close calls) in the van, never anything in the 80, and these are in braking situations.
I won't buy AT's, because they struggle to keep up on hardpack and are useless when it gets deep, which depending where you live can happen on the road, as you drive.
But this is Colorado, typically talking powder, with temps that can vary 20 degrees in a hour at night falls. You don't want a tire that freezes up quickly, like BFG AT's, in those conditions, because they can go from performing nicely to frightening in a hurry.
Having said this, newer Toyos are ok. They are nothing like trying to drive an old school BFG MT in winter conditions.
They are a hard tire and are not siped and tend to have a wide contact patch, but I suspect the comment above about intermountain west powder vs. coastal conditions is probably right on.
I'd sipe this tire if I was going to run them over time in winter conditions to let those big lugs flex a bit more as well as carry the basic biting advantage of siping.
I wouldn't take a sube over my 80 just because it was wearing them for sure.