For me the biggest drawback of v-drives is the draft limitations coupled with fragility of the rudder if you touch bottom. We had a 19' St. Tropez with a v-drive back in the late 60's and while exploring the back country in the keys, at a slow speed, bumped the rudder on the bottom and snapped it off. We got back 6 hours later by steering with an oar. Only maintenance issue I can remember was to keep an eye on the stuffing box for leaks.