Have had the Cardiology master and it works great. Whatever you do, don't get their light weight versions of anything. The master although more expensive has a longer warranty. Love the weight and cannot beat the sound clarity... If you want to compare I think 3m even has a chart somwhere on the site...
I would not rely on them providing a stethoscope... when I went 2 people need a steth and they only had 2... imagine if you were the 3rd person...