RGB Limited @ 8-bit provides a slightly better clarity and color accuracy compared to YUV420 @ 8-bit or 10-bit, but to me it's not worth the hassle of constantly manual switch color spaces between SDR and HDR/DV contents (especially considering those switches happens VERY often during mixed games/movies usage).
For this reason I would recommend sticking with 420 both for SDR and HDR when using Option 2 on PS4 Pro, and forget about changing settings, just enjoy contents.