First, I think scubalab measurement isn't entirely objective.
We were unable to recreate their results when we tried on our ANSTI machine. That being said I don't think ScubaLab was being duplicitous. At times it may seem like advertising dollars hold sway with Scuba Magazine, but that is of course their business model.
What people need to realize is the breathing rates they utilized are far beyond what anyone can realistically sustain while diving, let alone two people.
The rate limiting component on most dive regulators today is actually the tank valve. Most can handle flow rates higher than this bottleneck allows.
For what it is worth, I dive our regs beyond 200ft and know divers who go beyond 300ft with them and they work great. I tie into wrecks in this range, so they get a bit of heavy breathing while doing so.
keep in mind that the ANSTI has the regulator in a position with the diaphragm vertical instead of horizontal as it would be in normal diving conditions. This changes the WoB more on some regulators than it does for others. It is especially nasty for the exhalation effort.
Of other importance
It scored 5/5 in WoB under exaggerated normal conditions which is total WoB less than 1.05j/l at 37.5. That is something you can maintain for maybe 5 minutes if you're in good shape. At 75, you're going to pass out if you can even get there. Having the second stage handle that and purchasing a regulator based on that is a bit ridiculous imo.
Scubapro has obviously figured out how to do it with the S600, but in real world diving, you won't notice a difference and I think that may have something to do with the first stage more than the second stage as Poseidon wasn't able to get 5/5 on all of theirs though they do come detuned a bit from the factory and are capable of getting under 1.05j/l on the ansti if you tune it to beat the test. Question is more on whether the test is reasonable or excessive.
For me, the Deep6 gets great marks on the slightly exaggerated real world test and whether it fails on the unrealistic ones or not is not something that I personally care about or that anyone should really worry about when purchasing a regulator