Negatives about Spirit, I assume you know. You have to pay for EVERYTHING, including seat assignments AND carry on bags, unless they fit under the seat in front of you. The seats are EXTREMELY close together, front to back, closer than most any other airline. Unless something has changed, you don't get even a free soda on the plane. You also have to PAY to print boarding passes at the airport. So unless you have access to a printer in SXM, you will have to pay for that. If you don't pre-pay for bags (including carry on bags that have to go in the overhead) they charge BIG bucks at the airport. If it were ME, I would not book a connection on the return with only 1.5 hours. The other issue with Spirit is that they only have one flight per week (I guess that's still the case) and if that flight does not go, I think you might have a BIG problem, as Spirit does NOT cooperate with other airlines. What that means is that they will NOT place you on another airline if they have mechanical trouble. They presumably will try their best to get another plane there and get you there, even if it is a day or so later. But with other airlines, they will put you on another airline. Not Spirit.