I think LPH's advice about pulsing the snowplows is good. For icy downhills, you just have to dig those edges in and slow the snowplow down. The quality of the grooming makes a big difference, as does temperature and sun. You should try another place and experiment with conditions/ different types of grooming.
Days 2 and 3 in Stowe:
Yesterday was snowing like hell and wind gusts up to 30 mph. Out we went at Von Trapp (the hills are alive...). Once in the woods the wind was not much of an issue and it was not that cold. But, blowing snow had pretty much obliterated the grooming, tracks were non-existent and the packed lane was almost back country conditions. Two hours of slogging through that was enough! At the end, we were in open fields, and it was pretty miserable. Not hard terrain, but not fun. Chalk it up as a htfu experience.
Today went back to Trapp and it was perfect. Still some flurries, no wind and 30 degrees. We skied up to the cabin, ate lunch, and skied down, about 20k. It was not technically hard, but long. Tired but happy. No skiing tomorrow, we will shop and drive home.