In reply to ballsac: I don't have one.....but I'm also looking for a 4 season tent.
From what I can tell they seem tough, but heavy, maybe over engineered/too heavy. If I was going to the Himalayas I'd look more at the TNF/Mountain HW stuff, but I'm liking the look of the new Alpkit 2 person 4 season tent, they seem to get good reviews and are a reasonable price(but not extortionate - like the TNF mountain 25.
P.S. theres someone on UKC selling a TNF 25 at the moment!