Adobe has greatly improved the Proxy file experience. It's a couple buttons to create proxies for all the files in a given project. Then there's a toggle button to toggle between proxies and full resolution files.
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You can tell Premiere where to create the files (I use a scratch SSD). You can then save those proxies so you can revisit the project months or years later without having to recreate the proxies. Simply park the proxies and point to them. I'd say overall the proxie experience in Premiere is a good one.
FWIW, I edit on a pair of Dell 32" 4K monitors behind an NVidia GeForce RTX 3080 Ti (Founder's Edition).
Last time I tried to edit using FCP was on my G5 (which I still have). Back then it was a horrid experience. Everything had to be transcoded and god forbid footage was from two different cameras. I'm sure it's much better now.
D