I believe you will continue to see turbos on smaller and smaller diesels for quite a while now. The really do wonderful things for efficiency and emissions. The down side is obviously there is on more system that can fail. However, despite this post, turbo failure rates have been greatly reduced in the last few years by improved technology.
If you've had two turbos die you most likely have an oil system problem (but it sounds like you already know this). You can run without a turbo, but I wouldn't expect the motor to preform well at all unless you make a whole number of changes including replacing injectors, and possibly the entire high pressure pump, and obviously the intake system, and the prop.
If it were my boat I would find and fix the oil system problem, replace the turbo, and then keep up with oil the changes.