Using stainless can be problematic as it work hardens quickly, its hard to bend and you will need a good quality flare to mate with other components. Its only advantage is the corrosion resistance.
On the other hand Kunifer (90%copper/10%nickel alloy) is reasonably mallable and is tolerant to poorly formed flares because it will mould (to a degree) to steel connectors etc. Its corrosion resistance is as good as if not better than SS in salt conditions.
SS brake lines, braided lines excepted is a bling thing not for serious performance.
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