I grew up skiing in the 90's and early 2000's seeing this fad come and go (snowblades). They are "fun" but are dangerous if you are not a great skier. It's very easy to hurt yourself (there is a very short tail on the ski and most people ski leaning back with their weight). I see people lose control easier because there is no leverage on the short tail to turn them. They are very rigid so it can also be very hard on the knees. It seems that the ones you posted are longer so they would be more stable.
