I've become somewhat of a stethoscope collector. I have a basic one sided diaphragm that most rigs stock, a similar double sided, an omron sprague rappaport that I have used since emt school, two littmans, a classic ii and a cardiology iii which I found in an ancient spare rig that nobody claimed, replaced the tube and diaphragms for $70 and use as my secondary scope now, and a couple vintage bells.
I've used every littman currently made up to and including my cardiology iii, and I have to say, everything under the cardio iii is a pissing waste of money. The cardio iii didn't even sound good until I asked a cardiologist to show me how to use the tunable diaphragm and all of a sudden I could hear the fancy valve motion, squeaky bowel soundI and pinpoint the areas of gunk in a copd patient.
That all said, for ems purposes, the omron is better in so many ways. For starters, it's the standard stethoscope used by er docs at harborview, a level 1 trauma hospital. It's binaural, so two tubes, meaning louder sound. A flat projected diaphragm means that you get full contact and can even get decent lung sounds through clothes. Dual sides, bells, diaphragms, multiple earpieces and spare parts make it a long lasting bugger too.
I don't notice the creaking of my own knuckles with the omron, for lung sounds and bp's the volume is twice as loud as any littman, good in a rig or at the scene, and even though the sound is less crisp than a cardio iii, the overall volume makes it a better choice for us, and it's cheap enough to not worry about losing. Ear seals are faster, the bits pop inside the canal instead of the mushy balls littman uses.
I feel like a littman is a piece of jewelry for people in medicine. I have no need for a cardio iii. I only have it because I found it. If you need a new scope, buy an omron sprague-rappaport (it is heavy by comparison, but if a scope around your neck weighs you down, you need exercise...)
Linky
http://www.amazon.com/gp/aw/d/B000FERLKI?vs=1