I think the advantage it gives you is that you can optimize the mechanical structure of the rocket parts.
I speculate that the disadvantage is that a many extreme environments also have hard requirements on the microscopic material structure of the components - and that will also have to be managed at the extruder/nozzle (as well as in the temperature and pressure environment afterward). Getting the materials properties right is much more finicky than the mechanical scale printing. And might change when you change the mechanical design (e.g. do you is there more material on some corner - then that might cool slower, which might give you a microscopic weakness around the corner...). I think you'll need world class materials modeling to do that right - and you'll have to do all sorts of validation that produced parts are ok.
In comparison, the spaceX welding techniques have less to worry about - the weld itself as well as properties the change/arise around the weld - the rocket tube presumably already at it's designed material strength.
I speculate that the disadvantage is that a many extreme environments also have hard requirements on the microscopic material structure of the components - and that will also have to be managed at the extruder/nozzle (as well as in the temperature and pressure environment afterward). Getting the materials properties right is much more finicky than the mechanical scale printing. And might change when you change the mechanical design (e.g. do you is there more material on some corner - then that might cool slower, which might give you a microscopic weakness around the corner...). I think you'll need world class materials modeling to do that right - and you'll have to do all sorts of validation that produced parts are ok.
In comparison, the spaceX welding techniques have less to worry about - the weld itself as well as properties the change/arise around the weld - the rocket tube presumably already at it's designed material strength.