This is definitely something I am interested in as well. I have some impromptu stuff from a shuffled deck but am always looking to add more to my arsenal.
If someone has that set "From a Shuffled Deck in Use" please give the difficulty level.
I can perform a DL, Tilt, control a card to top, but not quite at the level of a pass or palming cards or side stealing. I am not just a card guy so I have never really excelled at cards because I give too much time to all aspects of magic using various other items.
I wouldn't want to get the set and then find out it is beyond my experience.
Also...does anyone know much about the Jon Armstrong set? Obviously that is not impromptu material but it is another set I was looking into.