The argument started with the meaning of resting system.
If you are deciding what to take for resting on Via Ferrata, it is easy to reduce the question to comfort and adjustment. The Petzl CONNECT ADJUST is a familiar answer, and I understand the appeal. I use it at belay or rappel stations where that fine adjustment makes sense. That experience has not led me to give it the same job everywhere.
The interest in Ypsilon came from looking at the complete arrangement and what it could offer in demanding situations, beyond the moment of sitting back. That is why I call this a resting system. The Climbing Technology Ypsilon, CT K-Classic and Petzl VERTIGO WIRE-LOCK became the combination that remained in the setup through years of use.
Two arms were part of the reason, not the whole answer.
The fixed lengths and two separate connectors offered something familiar and predictable. The broader idea mattered more than fine-tuning a single resting position. This was also why a single adjustable arm did not look like an equivalent replacement to me. An adjustable Y arrangement is a different comparison and deserves to be considered as such.
Those distinctions explain the preference. They do not make every possible use of the equipment appropriate or turn a personal arrangement into a general technique. The handling history belongs here; a technical examination of methods, compatibility and equipment limits is a separate job. The Ypsilon is not an energy-absorbing Via Ferrata set and must not replace the CAMP set in that role.
The return after two years changed the emphasis.
Coming back to Via Ferrata after a two-year break exposed needs I had not given enough weight. With less strength, I was less settled in deciding what to do and which arm to use. The long arm was used much more than the short. Knowing the lengths did not solve the immediate problem of reaching the one I needed quickly.
That changed the argument. Keeping the arms together, or putting them on different sides of the harness, was no longer a sufficient answer to organisation. I needed clearer separation and more immediate access. The system has to make sense for the person using it while tired and uncertain, not only when calm and arranging the equipment.
Recognition and access are different problems.
Two different carabiners can help identify which arm is which. That is useful, but it assumes a degree of discipline and control. When those are harder to maintain, something easy to distinguish can still be awkward to reach. I had been giving too much of the explanation to a feature and too little to the complete handling problem.
The next step in the system is therefore about access as much as identification: how readily the required part can be found, reached and handled. I do not yet have a final answer to all of it. Presenting the known arm lengths as though they settle those needs would miss what the return to climbing taught me.
Why Ypsilon remains while the system develops
The Ypsilon remains the familiar starting point after years in the setup. Its two arms and the possibilities I have been examining still give me reasons to keep working with it. The newer observations do not erase that experience. They tell me where the explanation and organisation need to develop.
If you are comparing resting arrangements, ask what you actually need the system to do and how you will manage it when tired. Budget, intended use and availability all matter. A device praised for one task may not answer the question you are asking. This page explains why Ypsilon has stayed and why the thinking around it is moving forward. It is not a progression or rescue procedure; the manufacturer’s instructions define the equipment’s permitted use.