The M+S rating does not help you much.
Some non M+S tires perform much
better than the ones labeled Mud & Snow. The only way to find out whether a particular tire is suitable for snow or not, has to be determined in comparison test. Some magazines run them every so often . Search the net for information. It's all out there - you only have to find it.
Narrow tires are not necessarily better in snow. It very much depends on how much snow is on the road, what consistence etc. On powdery snow 4 feet deep you need flotation, flotation, flotation - a 44 inch tire would be my choice if it only could be fitted to the ML (check what the guys in Iceland do on snow).
On wet snow an inch or two deep a narrow tire with aggresive mud terrain pattern will do very well. On hard packed snow 2 inches thick a fine tread tire (as narrow as you can get it) with plenty of sipes will do very well. On snow more than 4 or 5 inches thick narrow tires sink in too deep and bog you down, like in soft sand - a tire with flotation (wide and tall - the wider the better) will do best. Tread design depend on whether snow is wet or dry - wet warrants M/T, dry stuff warrants A/T pattern.
Confused? Me too!
Ergo, there is no tire that will be able to be really good in more than
one category. Get a tank!