I’ve used the Pile Brush for several months. The 1 1/2″ to 2+” shag carpet, you can’t really tell. If they are industrial runners that’s fine. Some times if you can’t secure them they move. Frayed fibers, wool and polyester fibers, I’d stay away from. It’s called “a vacuum cleaner on steroids” for a reason. What ever a vacuum would do, this is about 5 times the strength (against the nap). In Orlando, it was mentioned about brushes, that the main one is what is to be used unless you do a lot of wool rugs. Then you would use the “vegetable brush.” Also it is a real pain to switch over brushes. So I’ve heard.
Hope this helps.