It is fine. diligence is due before such a commitment. No jutting will not quite approximate the movements because your maxilla is static you are only jutting mandible , so mandible will be too forward in relation to maxilla.
Ask Gunson everything , chin etc... he is a better authority than ur Ortho on ur chin too so ask him about how the "button chin" will look post op and how to best address it. Idk , imho , I do not see a case for chin shaving.