Looks like you're going to invade a house SWAT Style on a meth lab or something. Still a nice find OP. I think it's a great idea, but if I was someone using that at my gym, they better ALREADY be in sick physical condition or else it would just look dumb. There was a guy that most people could out cardio that wanted to try the snorkel thing and everyone laughed and said "shut up, you have trouble running 5m's."
I am no scientist nor have done much research but since I am huge into MMA and have some buddies that fight I asked them and they told me it is hit or miss. So I bought one, the Elevation training mask, the mask that is fabric, not plastic, that does not cover the whole face. I ran some hills with it, and I thought I was going to die (in a good way), I have also used it rowing, which adds a little something to change up just rowing, focusing on breathing and calming myself down because of the difference makes me give it a Good rather than a Bad review. Hope that helps.