its sounds like a reasonable argument if you assume all divers follow the same path - i tried twins ( about 15 dives) and didn't like them so went to sidemount so using your muscle memory logic I should have my BO mounted on the sideI appreciate your thought process and the questions you are asking, I (along with many of the prominent CCR instructors in Florida and Mexico) have been there before. I used to use the same arguments against the GUE rebreather configuration until I really understood the “why”. When it hit me, it hit me hard, changing the trajectory of my career.
Your example of the screwdriver is an excellent one. However, if you look at it from the perspective of the “why” GUE configures it’s rebreathers the way they do, it may give you a slightly different result.
In your example of the screwdriver, the screw still turns righty-tighty, correct? Meaning, the core of the system is still the same. You might hold the powered drill at a different angle, but it’s function is still essentially the same. Now, imagine if someone said “well, the power drill is a different tool, so screws driven by a powered drill should turn lefty-tighty because it’s easier for me for whatever reason”. Then, when the power drill fails and the screw needs to be tightened quickly to, say maybe, stop a leak or something, old muscle memory for operating the screwdriver will take over. How efficiently do you think the operator will be in handling the “emergency”?
Within the GUE system, certain things like longhose deployment, valve manipulation, unclipping a longhose, etc. are deeply engrained into the muscle memory so they can be recalled efficiently and without thought. The ease of transitioning that core foundation to as many configurations and environments as possible is significantly higher, and far more efficient than changing everything each time. Especially when you expect to move from CCR to OC regularly as GUE divers often do (different tools for different jobs, but core function remains the same).
CCR diving is only dramatically different from OC if you make it that way. If you treat them similarly, it’s AMAZING how much it simplifies your diving and increases your overall enjoyment.