I have Denali Ascents, I have between 70-100 miles on them and yesterday I had my first problem with them.
I managed to crack the frame near the front coming down Jackson. I have no idea how long I was hiking with a cracked frame, could have been miles for all I know. I didn't notice until I reached 302.
There was a discoloration at this point on both sides (and on my other pair) indicating stress on the plastic. I encourage anyone who owns a pair to look (there will be a line lighter in color). I cauterized the crack with an old wood burner and epoxied the crap out of the area. Hopefully it will not crack again.
My only other gripe (which you will probably hear from other denali users) is they perform poorly when breaking trail in deeper snow. They just don't have the great floatation as the larger surface area tubulars.
Every other way they've performed like a champ. The side crampon "mega ice crunching teeth" kick ass. The televator is a calf saver on ascents -- it makes the steep bits seem like stair steps.