ROB wrote an answer about Scarpa Booster Climbing Shoe - Discontinued Vibram XS Grip on February 10, 2010
i own the solution and have tried the booster at a Demo. the Solution has a very pronounced "Nib" of rubber on the pinnacle of the Toe which focuses your weight to this minuscule point. Meaning that on roofs you can hook a hold with the end of the toe rubber. the Booster lacks this feature and also can have a bulbous heel that forms a pocket around your foot if it doesn't fit right.