I'm a Noveske fan and own multiple factory rifles. However, they are notoriously overgassed. But they are overgassed for a reason. John wanted reliability first and foremost. Overgassing his rifles plus his modified chamber design (in his stainless barrels) all were design decisions to reenforce reliability. The fact that he also knew how to finish his barrels consistently lead to better accuracy as well. But to use his rifles as an example of "correctly gassing from the get go" is not accurate. If reliability is your ultimate concern, then perhaps they are. But they certainly do not have optimally sized gas ports.
That being said, the point you raise about adjustment screws on AGB's adding another failure point is accurate. As I stated previously, I've had two SLR AGB's fail. They both failed by losing the detents on the adjustment screw. SLR quickly replaced/sent repair kits. But the failures still happened. I won't use an SLR on a fighting gun. This is also why I like Noveske's AGB. It is simple and as bulletproof as one can get. It is also the AGB I use on my "go-to" self-defense rifle. Suppressed or un-suppressed, it has give me zero issues.