yes, i shouldn't have spoken in such general terms. when i played lacrosse, i found the airway obstruction to be a barrier to performance, such that i actually would sneak mine out during games. but not everyone feels that way. i also have a deviated septum so the mouthguard wasn't entirely to blame.
mental obstructions to performance are just as real and sometimes more of a barrier than physical ones. i would never have been able make the kinds of defensive plays i did had i not been wearing a cup (and some guys didn't), that moment of hesitation can make all the difference.
by all means give it a go, good luck!