Are you going to Cuba to take photographs or to experience the culture and people ?
Maybe it's because I'm getting older but I really don't understand the need for a backup or multiple systems on a short trip. If you're working, yeah, prudent decision but a vacation ?
Bring your Leica, take some photos (b/w to be different, how many photos of colourful old cars do we need to see ?) and if the camera gets cranky, enjoy the place without the filter of a viewfinder.
Chances are, you'll probably go back if this trip is great and then you can finesse the gear selection for that trip.
Have fun and bring lots of things to leave behind as gifts.