I've had mine for about 3-4 years. You can pick up murmurs and crackles very easily with this model. Recently, I tried using my former stethoscope on patients (Sprague Rappaport), and WHOA!! I could barely hear anything!! (I had gotten spoiled by my Cards-III for the last few years without even knowing it!) Years ago, I was wondering how my classmates and residents (all of whom seemed to have the Cards-III) could hear murmurs and stuff, and I couldn't! As a resident now, I'm glad I own one. One day, I forgot my own Cards-III, and had to borrow a colleague's stethoscope (it was a Classic II SE). Even though her Classic II SE was also a Littman, I still couldn't hear as clearly through that, as I did the Cards-III.
On the downside, it is rather pricey. But I equate it to buying a good pair of glasses. In exchange for your money, you'll be able to hear a lot more.