You know, I have used several models and The more expensice littmans a great, but they are more expensive. I recently found the littmann select in the firehouse supply closet and put it into service on the ambulance, it has worked for me better than several of the more expensive models. I believe that it is due to the tuning ability, but all I know is I love that stethoscope.
What I am getting at is more $$$ does not always mean that it will work well for you, if you have a way to try a couple of models, maybe someone you work with has one, do it, but remember that something that works great for others just might not be the correct fir for you.