I'd lay money on not being able to tell which reg I'm breathing from (cheap crap excepted).
Pretty much. Though there could be some differences that show themselves at 300 feet. That's what I've heard about the Atomic M1 really shining. But those are rebreather depths in my opinion.
All I want is a reg that works (i.e. conforms to EN250/whatever) and a comfy mouthpiece which is the only material difference between regulators.
Pretty much. There is some difference in materials used that can affect servicing intervals, failure rates (as EVERYTHING fails eventually), etc. but that needs to be quantified as well.