I can see a use for these... 95% of the time I'm at a show I am wearing earplugs as hearing protection. Then between sets I sometimes listen to a little bit of what I just recorded, so switch to the ear buds.
I think I could wear these at a show... without feeding the ear buds sound from the recorder they kind of act as ear plugs, and they would record through the mics, without the above concern for interference. Then between sets play through the ear buds.
It's not a bad idea, I just wonder if the ear buds or the mics are very good, or if they brickwall at 100db.