awap:I really think I could get that overbreathing feeling with any scuba regulator. It's more a matter of what you are trying to do than a regulator quality thing. I've gotten stupid and gone off trying to outswim a turtle. I turned him but ended up winded enough that even my well tuned Mk20/G500 didn't feel like it was delivering enough gas. But the cure is fairly simple: stop, relax, and breath deeply. It may be uncomfortable for a minute or so but if you don't panic, the overbreathing feeling will pass.
Perhaps we are saying the same thing but with a somewhat different concept of what "overbreathing" means. I agree that a properly functioning regulator will deliver enough gas to sustain you.
Correct. A CO2 hit makes your breathing rapid and shalow, so extremely inefficient. I had to force my self to breath deeply. If I hadn't done that, the situation could escallated quickly. A bailout bottle (7 liters - 50 cuft?) doesn't last very long at a high breathing rate at 150 feet. And I had a deco obligation of over 30 minutes.