Do Tunable Diaphragms Really Work?

I am in my fourth week of nursing school, so to say I'm a novice at auscultation is a VAST understatement .

I was given a Welch Allyn (sp?) Professional model by a friend, but in my frustration to hear BP, I was convinced it was the fault of this 'cheap' stethoscope (I have since researched the quality of the WA and realized I was a fool).

Regardless, I went to my school book store and bought a Littman Classic SE II based on everybody's recommendations. I find the Littman is louder in terms of taking an apical pulse through a shirt (but not by much), otherwise it seems kind of 'boomy' to me. I guess i was expecting a huge difference between the Littman & the WA...

Is the tunable diaphragm really all that great? Is it recommended for a new nursing student? The difference in required pressure seems like it would be uncomfroatble for a patient who is very young or suffering from cachexia. Is everybody here sold on the function of the tunable diaphragms? Are there any traditional diaphragm/bell steths that are good for a new student, or should I just keep my Welch Allyn? Thanks!