Can only comment on AA flight 2219 leaving at 12ish......never ever had a problem. This leaves from Miami direct to SXM and usually is on time or up to 20 minutes early. Must have done this flight about 30 times. Return around 4.30 so gives you virtually half an extra day. Also on time. Just for those coming from Canada and elsewhere across the country who want to say combine an overnight stay in Miami and possibly enjoy some time in Miami by sightseeing. They do though tend to change the departure gates this trip 3 times in 45 minutes but no big deal as was in same terminal. Also as mentioned before try to travel midweek if you can.