I did a few cruises to the Bahamas
and keys with a 9.9 long shaft on a 26-foot Westerly Centaur. While overall I prefer an inboard, I have to say the outboard got me where I wanted to go affordably. I motor sailed in seas of up to about 8 feet. The biggest problem was not so much ocean swell as standing waves caused by wind
against currents such as in inlets.
Positives I experienced: Much less expensive, can throw it on the car to take to the shop, simply throw it in my basement to winterize, easy access, common fuel
for boat and dinghy
motor, less weight, provided more storage
Negatives: Easier to damage or have stolen, less fuel
efficient, prop coming out of the water or head
getting plunged, more volatile fuel.
While it served me well, I have to admit that when sailing in wind
& waves the potential of plunging the head
or the prop coming out was a constant worry for me.