Are you able to say who exactly this is that has offered the job? To me it sounds like basically a first aid training company. Not to sound too negative, but no matter how much you like teaching, first aid is not the most exciting thing to teach, especially for a paramedic who knows that most of what you're teaching doesn't matter.
If this were more like a college instructor position where you would be teaching paramedic students I would probably be much more positive about it for the reasons that others have mentioned.
If you drop down to PT, do you maintain your seniority to be able to get a FT spot back if you change your mind?