I've done both the Main Trail and the Mountaineer's Route a bunch of times in winter. They each have their pleasures (and displeasures, I might have said, but I cannot speak of displeasures in these mountains--even in the wildest of storms!).
Technically, the MR can be considered tougher than the MT because of the 400' above The Notch. Elsewhere the technical difficulty is about the same, with the MR chute equating roughly to the chute below Trail Crest.
But in terms of total effort, I view the MT as the tougher of the two because of its
length--11.2 miles vs 4.1, plus the walk from where you have to park to the Portal. (Although that 11.2 miles is considerably shortened in winter, when you are off the trail a fair amount.) The hike to Trail Camp is always a nice stroll through beautiful winter landscapes, as is that to Iceberg Lake. And the two chutes are roughly equivalent, as I said. But above those chutes, while the MR has a 400' remaining climb to the summit, the MT has a long two miles to go. Last weekend, the snow conditions meant that those two miles would take as much as four hours, and almost that long to get back to Trail Crest.
And, speaking again of last weekend as well as the weekend before, I observe that most parties this year are going up the MR, leaving the MT relatively vacant. Crowds are particularly bothersome above Iceberg Lake, whereas the same numbers of people anywhere on the MT are hardly noticeable.
All things considered, I personally prefer the Main Trail for the overall winter mountaineering experience.
My pictures from last weekend:
http://www.flickr.com/photos/rockwellb/sets/72157623682223366/And Bob H's:
http://www.flickr.com/photos/rescuebob81/sets/72157623679250018/
