Yeah, sure have. I purchased the Littmann 4000 Electronic stethoscope a couple of years ago for veterinary work, and find that it works well. My hearing loss is about 40db across the entire range. The thing people mostly comment on when using it is that lung sounds are a lot clearer than with acoustic stethoscopes. It takes practice to use, as the sound is quite different from normal stethoscopes. However, this is aided to some degree by the ability to record sounds fairly easily, and to upload to computer via infrared. These can be stored on computer and played back using the stethoscope and the sound played back is exactly the same as the sound actually heard, so can be used to self-teach to some degree. Anyway, it is quite a neat little unit, I do recommend it. Unfortunately, I can't comment about the other E-stethoscopes out there because I haven't used them myself. If you want any further info about from me, you can email me at corrie_croton@hotmail.com