Volvo Sail Drive
I used two of them during more than 13 years. No problem at all.
The last one, on a Frers 36, I used it during 10 years, and never needed even to change the hull gaskets; despite I checked them every season.
Maintenance is clean and easy.
Aluminium folding prop did need replacement after 5 years.
But as said by the other colleague, no leaks, no vibrations, no aligment. The hazard is that you won´t notice it is there.