Food Safety side you want to cook any ground meat to 155 for all but poultry and that is 165, unless cure #1 and cure #2 are involved. But that is another story, we are talking fresh sausages, so 155 for all but poultry and then 165.
Most fresh sausages are cooked hot and fast on grills and skillets, so they don't lose much fat. As pointed out earlier, when smoking fresh sausages they are cooking a lot longer, so they will lose or render out their fat and seem dry. If you cook at a lower temp to get the smoke penetration then finish in a pan or on a grill to get a bit more color if desired. I would not boil after smoking, you will lose a lot if not most of the smoke flavor. Unless they have either cure in them, they need to go to 155 for all but poultry and then it is 165.