Does anyone know the difference between the Homedics Therapist Select Shiatsu massage cushion with heat and the Homedics Total Coverage Shiatsu massage cushion? I want to get my boyfriend one of these for christmas but I don't know the difference. I'm guessing the total coverage just might be wider? And also, I know it has a shoulder massage option. But can you use the shoulder option AND the back massage at the same time or only different times? And any good or bad reviews on either ...Thanks so much!