Now the question I want you to answer. Let's say the only goal is to teach someone intermediate to carve clean or railroad tracks exercise. What ski (specific model or just derscirption like stiffness, sidecut, etc.) you'd choose for this? SL:11 she uses is 2005 model with somewhat longer sidecut that the same model before and after, I think it is 12.5m in 150cm.
So do you think if she can not do railroad tracks on her skis she'll be able to do them on any other skis? Please discuss ski, not pressure and balance skills of this particular student.
Until she's fore/aft balanced and engages the front of the ski, no ski is going to cleanly carve for her. Exactly what ski is the right ski depends on physical factors (think you posted them somewhere here) and her personal preference. Obviously you should try to have some influence in the selection process.
When I encouraged my wife to demo,demo, demo, I purposely put her on a few skis that were too much, just for her to experience the difference. She's not a gear geek, so she had no idea. She chose the Volkl 4 Stars out of the whole rack of stuff she tried. It was a reasonable ski for her. I'm pretty sure she wouldn't have walked away with an SL:11 if she had settled on that - I do fantasize that I have some influence.