A few points from our experience. When we started visiting SXM some 10 years ago, we did use Travelers Checks. Now it has become more difficult to obtain TC's and to use them on the island. Several years ago, we stopped and went to mostly cash.
Secondly, we always used the safe in our villa/hotel/condo for the majority of our cash. Earlier this year, we discovered that our safe was opened and a portion of our cash taken. We have learned from this experience and while we will continue to use the room safe, we use additional tactics to safe guard our cash.