Yeh, I'd go for the Classic IISE. It's cheapish and it's all you'll need for many years (possibly beyond intern years) as long as you don't lose it. You'd really only need a better one if you're going into physicians training or something like that.
And in terms of med school itself, it's probably better. Using the Classic will help you get used to flipping your steth for the bell/diaphragm appropriately, which is important for getting marks in your OSCEs since it's fairly obvious when you flip it. I've lost marks in OSCEs and such before because I apparently didn't switch to the bell for certain areas. In fact I did, but I just brought my Cardio in and it has them both on the same side and is changed by pushing harder instead, but the examiner clearly didn't know this.