I understand why you dont want to get stamped by the consulate. Nonetheless, it is always the better option to keep your non-immigrant working visa status, until you are granted the green card status, just to make sure that you will have a "plan B" if ever something goes wrong with your application. Don't mind going to the consulate for stamping, as an H1B is a dual intent status. If you enter the United States on Advanced Parole, you will be tagged as "pending adjustment of Status" and employer will not be able to change you back to H1B status.