Thinking of picking one up on sale to use at schooling shows. Uncertain what to order for size. Dressage Extensions lists them as 8R, 10R, etc., but there is no information as to how they run. For example, I know that in Grand Prix hunt coats I need to size up considerably; I am a street size 8-10, and I wear a 14 in a GP hunt coat. Does anyone know if I need to size up that much in HORZE brand?