I picked up a pair of these at GC about a month ago. They are not as flat as my Sensaphonics/Etymotic plugs but they are a fraction of the cost. Other than a bit more bottom end than should be, they don't do anything evil to the sound. The Westone molded plugs I used to have took the body right out of the snare drum and made it awkward for me to tell what I was doing dynamically. And the Hearasers are much more comfortable than the Westones and far beyond a set of Hearos I had previously. They also seem to stay in well and are more innocuous than the molded plugs. And you don't look like Lt. Uhura like the Hearos.
The bit about using the natural pinea of the ear and being down in the canal really makes a difference in how natural things sound. While the Hearos and some others have some amount of highs, they sound like listening though straws. The sound is not natural. Which leads many musicians to go without.
The attenuation of the Hearasers isn't that great, but it's enough to knock down the levels so that you probably won't aggravate things, and unlike the time I tried 25dB filters, it doesn't sound like the rest of the band is out in the parking lot.
I'm getting an extra set for my wife. We used to put bits of cotton ball in our ears when going to see music but these are much better. Probably not great for a hip hop club due to the lack of bass attenuation, but for seeing bands in bars and small clubs, they're great. Best $40 you can spend. I'm after all the bartenders I know to get some.