That's one way, I assume. Their prices have been really low, since they introduced that route.
As far as 'inviting disaster', do you mean because you would be booking two separate tickets?? The times on the Jet Blue flight pretty much assures you will have to overnight in FLL, so hopefully on the way down you won't miss your connection. On the way back, there shouldn't be weather delays in either SXM or FLL, so if you book plenty of time between flights, you should be ok.
If you mean something else by 'disaster', please explain.