Big E is right. The SS is not a cheater ski, it is a ski that doesn't create bad or cheater movements, it creates better movements as you use it, because it leads you toward making good movements. The Nordica and Atomic skis do the opposite. Look if you don't like what we say here there are other options. We aren't here to tell you our skis are better; we are here to tell you what is dangerous, and to help make better decisions.
Just as Big E stated, it's ridiculous to ski on a ski that hurts you. I skied the Nordica SL ski for one day, my knees hurt for a week. I skied the Volkl for two days, they are so stiff my knees hurt for a week. I ski on my Head Slalom skis and my iSS and my Monster 78 all day, all week and my knees, even my bad knee is OK. I have an instant feed back loop, if the ski hurts my right knee in the first run, I'm usually going to suffer. Diana had the same reaction with a Nordica 78 wide ski she skied, her knees hurt for a month. The torque required to stay on those skis is excessive even if you know how to ski really well. Diana knows how to float in transition and to load a ski. She doesn't force a ski to turn. If she has these problems imagine how skiers who are trying to steer these skis will end up?
I think it's been said, but if you find SS too easy and you think you ski too well on them and you need a challenge, just make better turns. Hey I can challenge myself by trying more demanding turns on SS skis. I test my skiing by trying to make better turns in difficult situations by using good movements. I don't go out and get a ski that will be really hard to ski on and try to make it conform. I can do it, I've done it all my life on straight skis, but I knew what I was trying to do. It was not fun.