There weren't any OLED displays in 2001 that I am aware of, so that might be a typo. I have heard of many people using the 4800 on OLED displays without an issue. My LG is not OLED, but my 4800 looks great on it.
With the C1, the 4800 will provide Dolby Vision and standard HDR. I believe it will also pass HLG, which is another version of high dynamic color. I know I've seen HLG on mine, but I can't recall if it was while using the 4800 or the Nvidia Shield.
If you decide to try the 4800, remember to go into the settings after you've completed the initial setup and disable HDR Always On. If you don't, it will trigger your TV into Dolby Vision mode all the time. This will result in inaccurate colors on non-DV material. I've watched DV material on HBO Max, Disney+, Vudu, and a couple of others. Even on my non-OLED display it looks great with the Roku.
If you're running the 4800 through an AVR (I imagine with that display you are), make sure you change the audio output to auto-passthrough, or the 4800 will convert everything to Dolby Digital.
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