Knicks- It might if old techniques are proven ineffective, better techniques are uncovered, or equipment improves. I doubt a couple years makes much of a difference though.
Bates is a decent reference and the patient's expressions can be pretty amusing, but if you find a better reviewed CS book get that. It's a little disorganized but you can usually find what you want to know. Being a good practitioner starts with good clinical skills. It's definitely imperative to have a book so you can check your technique as you are learning to do physical exam.