Littmann Floating Diaphragm Really Work?

I know Littmann is a popular brand, but does the floating diaphragm work well in practice? Is there really a difference in the frequencies that you hear with the changing pressure? Do you find it easy to change pressure on a patient and still get accurate sounds? When pressing firmly, does it cause the patient discomfort? As a student nurse, should I seek out a tunable diaphragm or should I start with a standard diaphragm/bell setup?
Sorry for the over-loaded questions, but I want to start my nursing clinicals with a solid foundation of auscultation.

Thanks!