Just back from SXM. Overall a positive experience.
Booked economy, got economy: Hyundai i10 1.2 auto—a true gutless wonder—with French plates. Everyone was friendly except when I enquired on a Diamond upgrade: hostility and physical aggression from the shuttle driver in response.
Car was dinged up, but noted and OK upon return. Deposit of 2x rental cost was held on my CC.
Other than the aggression from the shuttle driver, I would rent from them again.