But those are my preferences. Now I’m not trying to say GUE are wrong, their course their rules after all. But I want to know why.... Why are comfort harnesses frowned upon, what reasons and what’s the data to back up those reasons?
Before someone chimes in with the “failure points of plastic buckles” line I request you back this up with real world proof rather than some anecdote passed down from your grandmother about your scuba diving hamster etc.
You ask why, then immediately proceed to disregard the answer that you know is coming. That makes it a bit of a loaded question IMHO.
GUE...and, in general, those who follow a 'hogathrian' methodology to equipment configuration view comfort/deluxe harness as unnecessarily complex and containing more failure points than an equivalent 'bare' webbing harness.
There's no need to provide evidence or record of QR buckle failures. The simple fact is that a QR buckle could break, wheras nylon webbing, without a QR buckle, will not.
I can drop a cylinder onto a QR buckle...and onto bare webbing, if anyone wants to argue the toss over that point...
Beyond that, in 25 years of diving.... I've seen a few QR buckles fail. Sometimes those failures weren't evident until during the dive (hairline cracks). I've never seen a bare webbing harness fail... they don't fail, they wear out. It's easy to diagnose and replace a worn harness.... inconceivable that anyone could dive a bare harness to the point of failure without noticing it has degraded.
Technical divers....and the principles they follow.... tend towards minimizing risks whenever and however they can. That mindset is universal across tech agencies and instructors. What differs is merely the calculation of what constitutes a risk and how that is perceived to weigh against the benefits.
GUE tolerates little risk of failures. In addition, they see little need for adjustable harnesses. A bare webbing harness performs quite effectively and has no weak links. The critical aspect is that the harness itself is set-up and sized properly.
Some technical divers might have physical issues (mostly shoulder mobility) that make a non-continuous harness more desirable. That's a valid argument for many.
Other technical divers might state that they need an adjustable harness so that they can more easily configure between different exposure protection, when travelling around etc. That's less valid - arguably - as it favors convenience over safety. Technical divers are taught not to compromise safety.
These factors DO NOT apply to recreational divers. Recreational divers are not generally taught to dive with this strictly risk-adverse mindset. There is good reason for that.. Recreational diving is generally a
very forgiving activity. Failures, mistakes and errors do not have a catastrophic or damaging consequence in 99.9% of occurrence.
Technical diving is
not a forgiving activity.... and the more advanced the technical diving becomes, the less forgiving it becomes. Until the stage is reached where an unmitigated error or failure has a near certain probability of death. Hence, a very different mindset applies.... and this mindset is encouraged from the outset of technical diving training.
GUE...and some other tech-focused agencies, adopt a 'beginning with the end in mind' philosophy to training. For that reason alone, they promote a technical diving mindset to their recreational level divers. It's not for 'now'.... it's for 'later'.
The best way to view the issue of failure points, and other equipment decisions, is by balancing risks and consequences...
Risk of Failure versus
Consequence of Failure.
The risk of failure of plastic QR buckles is debatable. However, it could be said that they are higher risk than metallic attachments. They are definitely higher risk than no breaks in the webbing at all.
Now, let's consider the consequence of failure. This is
absolutely dive activity dependent. A QR buckle failure is probably nothing more than an inconvenience on the average recreational dive. It would be hazardous on a technical dive, where the harness might be supporting 4-6 cylinders. On a long-duration, exploration, cave dive in high flow, or using a scooter... it could be much more than hazardous.... it could be catastrophic.
Small risk of failure versus small consequence of failure: Fine....go for it....
Large risk of failure versus
small consequence of failure: Best avoided, but you'll probably "get away with it" when it happens.
Small risk of failure versus
large consequence of failure: Nope... don't go there... not worth the risk, as it is avoidable and unnecessary.
Large risk of failure versus
large consequence of failure: Suicide. You'd be an idiot.
There's a lot of 'grey area'.... but it's always a personal decision. That decision is based on what you've learned, what you agree with, your personal acceptance of risk, your awareness of risk mitigation, how you dive... and how you plan to dive in the future.
But remember my rules say you need to back up your statements with evidence.
Strategies for risk mitigation is part-engineering and part-
philosophy. When it comes to someone determine their own
personal safety, I don't think that anyone is beholden to produce facts, figures or statistics.
If a diver is properly educated on the risks and consequences of the diving they undertake (or plan to undertake), then they are capable of determining what balance of
risk-mitigation versus
risk-acceptance they are comfortable to tolerate.
For me... I don't care if QR buckles only fail in 1:1000 or 1:100000000 incidents. If I don't
need to add a QR buckle and there is
any risk of failure, then I'll err on the side of risk avoidance.
Others may decide differently. That's their prerogative.... and there's myriad factors that'd determine why they choose an alternative approach.