The Montserrat runway is quite challenging, for that reason I would never board one of those planes to that destination as well as other short and crazy airstrips in the region (Saba island). I always do my research before embarking on my "air ventures in the Carib..." and many times opted for a safer....... boat ride.
Although Saba is a challenging airport, if you consider that there have been no accidents at this airport in it's history (50+ years?) I'd say it's pretty safe to fly there.
Winair is the only scheduled service and I can personally attest to the very high experience and training requirements that Captains require to fly in there. As well, there are very strict and conservative wind guidelines for both landing and take-off.
Montserrat is not nearly as challenging as Saba. As for the training/culture of FlyMontserrat...I'm not sure