The rubber feet hold surprisingly well! In my basement I have sand bags that i put on the supports on the legs and weighs it down perfectly. Also, those little orange vises are EXACTLY flush with the board so the scraper doesnt get stuck on it!!!!
i use almost exactly the same thing. mines at least 10 years old and looks a lot heavier than that, but it works awesome. not as good as traditional vises on a workbench, but it gets the job done. i do at least 3 boards and 3 pairs of skis every week with mine.