I'll have to see if the UB420 has the slider, but I used the Harpervision settings and set my Panny to HDR, Epson to SDR and man to my eyes it is far better than any other settings I've tried from this thread thus far. I've A/B'ed all of them and this has the best blend of really good blacks while maintaining decent shadow detail (there's still room for improvement, but I think that's looking like a JVC) and amazing colour. I threw in Aquaman and was blown away. I'm still tinkering and I doubt it will work, but I'm going to try and hook up my Darbee and see what happens.I have some fantastic settings for Digital Cinema mode that using the Panny UB820 doing HDR-SDR conversion. With they dynamic slider pushed up you get the brightness you need and the color filter looks phenominal.
I have the Shield too and unfortunately not finding I can replicate without the Panny doing it's thing. Keeping with Harpervision at the moment and looks great. To my eyes much better than Rec 709 1080p.