I have not tried them because I worry if one shifted, or slipped there would be a sudden change in pressure thus undoing any slow equalization process.
Nothing to worry about there, I don't think. I actually lost one at some point during a dive and didn't even notice until I surfaced and noticed I could hear 'too well' on that side. It's not like there's a huge pressure differential between the inner and outer section of the earplug. After all, there's a hole in it! I would think it's more of a modulator as to the speed of pressure change against your eardrum, but the change is still going to happen pretty quickly regardless. I don't know the exact mechanism of action but NDL_Diver's explanation sounds reasonable. However they work, they do work, for me at least.