SomnoMed Herbst Mandibular vs Dream TAP Oral Sleep Appliance

I was diagnosed with moderate sleep apnea in 2011, which progressed to severe sleep apnea in 2023. I have tried CPAP in the past, but could not tolerate it so I went the oral sleep appliance route. My first dentist supplied me with the TAPIII in 2011, which had worked successfully for years reducing my snoring and episodes. However, this appliance detoriated over time and needed replacement. So, I went to a dentist, whose expertise is in dental sleep medicine, and was fitted for the SomnoMed Herbst Mandibular Sleep Appliance. The problem is this appliance does not keep the mouth closed even with the rubber bands installed in the front. The DreamTAP doesn't have this problem because the hook in the front keeps the trays joined in the middle. I questioned the dentist about this and was told the SomnoMed is better for the teeth because the pressure to move the jaw forward is on the stronger back teeth, rather than on the weaker front teeth. The problem is I wake up with bad headaches in the morning using the SomnoMed Herbst, which I didn't have with the TAPIII (replaced by the DreamTAP). Has anyone experienced this using a dental appliance? Is the DreamTap a better option for me than the SomnoMed Herbst? Any insight will be much appreciated.