Re-read the two posts above as they are spot on.
I often hear about divers who try to artifically lower their air consumption and in the extreme this leads to skip breathing where the diver uses an inordiantly long pause either between inhalation and exhalation and/or between exhalation and inhalation.
I idea is seductive as most divers quickly learn that the O2 content of exhaled air is still about 16% O2, and its even higher for nitrox as in either case, you use only about 5 percentage points of O2 from a single inhalation of any mix. Way back in the day when nitrox was still voodoo gas many divers felt and or claimed to be able to greatly reduce their gas consumption on nitrox. Those you did however, also had greater issues with narcosis, and per some early US Navy studies (1950s) into oxygen enriched air mixtures they were also at elevated risk of ox tox as elevated CO2 exacerbate both.
What people tend to forget or be ignorant of is that your brain triggers your breathing repsonse not due to low levels of O2 but rather to high levels of CO2, and your ventilation rate is what keeps the CO2 levels low in your bloodstream. So by suprerssing your ventilation rate to improve your gas consumption you are increasing CO2 levels and the narcotic properties of CO2 at depth exacebate the effects of nitrogen narcosis.
Personally I get a bit annoyed with technical divers who put excessive stock in low gas consumption rates and consciously or unconsciously reduce ventilation rates (and increase CO2 retention) in the quest for a better SAC rate and/or to not be THAT guy who is the first to turn a dive on gas. They should know better.
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Similarly, Herman is correct that a high flow port means little as it is not the limiting factor in a regulator. For example, in terms of first stage performance a Scubapro Mk 2 will flow about 90 SCFm, a MK 17 flows about 177 SCFM, and a Mk 25 flowa about 300 SCFM - but the highest flowing second stage available only flows about 65-70 SCFM. In that regard second stage flow is the limiting factor with a range fo performance from about 30 SCFM to 70 SCFM.
That said, at depth, a lower performing reg can start to lag due to excessive drop in intermediate pressure and it can in some circumstances become possible to over breathe a regulator where it begins to feel like it is not delivering enough gas to meet your instantaneous inhalation needs. But generally speaking with a high performance second stage and a first stage that flows at least 150 SCFM, it just isn't going to be an issue even in deep techncial diving.
If high flow ports do anything at all they create a bit more of a venturi effect in a diaphragm second stage and help the response time of the first stage a bit, but any difference noticeable at the second stage is minimal if the second stage has adequate performance.
On the Mk 25, the end port in the swivel cap gets air directly out the end of the piston,and it does flow about 10% more gas than the other ports. But again 300 SCFM is of no more use than 270 SCFM when the second stage can only flow 70 SCFM. Those first stage flow rates are determined with a 3300 psi supply pressure through a valve with gobs of flow rate and are measured by just removing the port plug - eliminating the otherwise limiting factors of the hose and the second stage, so the numbers have little real world relevance.
