Not to add to your uncertainty, but I think that, as RayG, points out, that the probability of being moved is very low but just isn't zero. I think that the route you are on, and the specific time will have a bearing on how low the probability is... for example, departing or arriving SIN around CNY or around the beginning/ending of historical vacation travel time for residents of Singapore might increase the probability by some amount. IMHO is to stay with 1A to be certain of your seat assignment, and if 1F is still open a few days before your flight, then maybe consider grabbing 1F. And if this is your first flight in Suites, I can't imagine you'd be disappointed in any Suite. Now your other potential situation is if you are traveling solo and have either 1A or 1F, that a couple traveling together but are in some combination of suites other than 1F/2F or 1A/2A, and they ask the FA to try to move you so they can enjoy a combined Suite.