The answer depends on the rider, I would say. I have soft lenses and almost never have problems, whether I'm on a coaster or just sitting around. In the 4+ years I've had contacts, I've only lost two, and neither were on coasters (one was at Blizzard Beach, but that's not quite the same).
So my answer would be that you shouldn't have a problem with them unless you have problems often.
Hope this helps.