I am a senior citizen; 5'7" 140lbs advanced skier, just learning moguls now. My go-to ski is a Blizzard Brahma 173mm; 88 underfoot. I want to get a pair of skis JUST for learning to improve in moguls. I am told I want shorter, and narrower. Some tell me stiffer, most tell me softer. I am looking for about 160mm length, 70-76 underfoot. Softer usually means beginner skis, which are plentiful, but I don't want to make a mistake. Do I want soft? Is beginner ski OK? Any recommendations? Thanks!!