One thing that has not been addressed is cleaning and feed speed. The platen, grit and friction rollers need to be cleaned to prevent slip and drag at high speed that occour AFTER the reg marks have been read and compensated for. Slick back material like controltac slip more easily at high speed feed rates. Also feed rate—if the machine reads the reg marks at slow speed and then cuts at high speed the outcome can be different as the "control" has changed. We've been contour cutting prints since way before automated reg marks and have worked through almost every issue. I do find that cutting anything under .5" tall I cant run the print must past 12'-14' without some minor drift on the plotter, even with automated registration.