I wouldn't let a car theft or two influence your decision, just be aware and be proactive. A car theft can happen anywhere, anytime and I would bet that most larger size properties on the island have experienced a car theft or more over the years. If you are happy with the unit and the price is good than make sure you take theft insurance on the car rental that covers theft with 0 deductible and than you have no worries. $100 added to your car rental might give you piece of mind.
As in the US, Kia's and Hyundai's are the most stolen cars on the island, maybe avoid those brands. Also, you might ask your car rental company for a car with French tags as they do not reference rental cars with their tags.
.
