I will swear by my Seacure. Once selected for proper size, molded (and can be trimmed!), they last and last and "float" in the mouth. No jaw fatigue, you almost forget it is there.
The only problem with taking one's own and using rental gear is you may find that unless you take two gauges, one will not fit the reg you are renting.
I've used Seacure for at least ten years and have recommended it for many dive friends and family - one with TMJ loves it. Two big thumbs up from this diver with over 55 years of diving.