|: I can't imagine this contraption turning like a roller skate. On the one hand, the wheels don't have opposing partners. I'd say that will be very strange when you shift your weight. I think it would feel like a suddenly changed wheel base. And on the other hand, it does not have steerable trucks. I think it would feel neither like a roller skate nor like an inline skate.
I really want to try one of these out just to see what they feel like in use! I can already feel some benefits just thinking about it! But, not for extreme skating. More for casual skating and cruising.