when watching roadracing, motox, RacerTV (covers the GNCC series), etc. .. pay close attention to riders just getting ready to go out, or just getting in and taking of the helmet. (like just prior to getting an interview) You will see lots of em with a mouth guard. Same with ear plugs. Now that it's "on your radar" .. you will spot em more and more. not saying ALL, but way more do than don't. and the reason i like the one pictured (shock dr gel max) you can breathe in/out pretty easily while keeping your mouth closed. SO, it's actually easier to breath with this thing in than not wearing one at all, and you get the added benefit of reducing the likelihood of huge dental repair bills. I have read it can reduce chances of concussion too..
lol.. most will try to get it out before the mic is shoved in their face, but you get to see the occasional dreaded "saliva string" as they pull it out..
My dentist is actively against the boil and bite ones. Short form - almost guaranteed to end up with the wrong fitment and will cause issues before they'll prevent any for most people. After going through what it takes to make one right, I can see where he's coming from now. Edit: I should note, he's all for them for the protective function, just not the boil and bites.
I use the boil and bite, curious as to why you are guaranteed not to end up with the right fit? Mine feels like it fits perfect, what does he say the main fitment issue is?