@Herk_Man: Wouldn't descending slowly (under control) accomplish the same thing? Overweighting can contribute to out-of-control descents, and we can all see how descending faster than one can equalize can be dangerous/painful.
I've thought about the design of the ProPlugs. If the plugs work the way the manufacturer says they do, essentially they create another air space between the water and the eardrum. Ear pain experienced during diving occurs when the eardrum is pulled inward over the ear bones due to increased ambient pressure (relative to pressure on the other side of the eardrum - in the middle ear). This is mitigated by allowing air to equalize on the other side of the eardrum - air flows from the respiratory tract through the Eustachian tube to reach this air space. The only way that the extra space on the outside of the eardrum can help is, during descent, if the extra space experiences a "squeeze" of its own and helps pull the eardrum off of the ear bones. This would be akin to a suction effect on the eardrum pulling outward. I could see how this might buy some time while the Eustachian tubes on the other side of the eardrum do their job.
I've probably read a lot of the same "reviews" that you have. I don't know anyone personally who has used this product. I'm very skeptical of the manufacturer's claims since they make no sense based on what we know about ear anatomy and physiology. It would be very easy to conduct straightforward "scientific" testing to backup the claims. Curiously, those haven't been done.
