Dan,
If you go to a trained sleep dentist they will choose the proper appliance for you. Many factors are invovled TMJ problems, grinding, size of muscles. Any dentist worth going to for these appliances will be trained in choosing the right appliance for you. My personal preferorance changes from patient to patient, yes I have a hand full I prefer to use but they don't always work for that patient. This is why the Academy of Dental Slepp Medicine trains doctors to decided on the prtoper appliance for each patient. It should not be a choice of what the doctor likes but what the patient needs. Check the qualifications of any sleep dentist you go to . The best are obviously diplomates of the society we have been through extreme testing.