Sorry for this, I'm sure this has been done before but the search function is down. I need a new mouthguard and am 95% sure it will be an opro. Has anyone had any bad experiences with them? What's the difference between the Medium, Heavy and Pro Impact? I want something I can still breathe with but will also stay on my teeth (every time I open my mouth my $0.99 mouthpiece falls out). Anyone know what the turnaround time to receive the molding kit, and then the actual mouthguard? All comments appreciated. Thanks.