My 2 cents on the Vizio P-Series.
Ok. Well THAT was a long day and night.
Short version: The Sony 75X780F is still an exceptional TV and to do better, I need the X900F.
Long version: Lots of surprises here, but this turned out to be a contest between the top notch product of a lesser company (Vizio) featuring major FLAWS and half-baked features that just don't deliver vs a mid-level set with LIMITATIONS from a legendary dependable company (Sony).
What it does right: It get's dark. REALLY dark. And it has peak brightness enough to achieve strong HDR performance in and out of Dolby Vision.
What it does painfully wrong: 1. The blooming around bright objects on dark scenes is like nothing I have ever seen. It's bad. Really bad and really distracting. 2. There are way too many scenarios where you actually see the local dimming move from square to square. It's not subtle. And for a TV costing this much, it is inexcusable. And yes, I adjusted all the settings and tried with many different options. No bueno. 3. In so many scenes with bright content, you see banding. The worst I've seen on any monitor/tv set. I tried multiple sources, multiple resolutions, multiple settings. Nothing got rid of it completely.
For hours and hours, in light, then in the dark, I played the same content on both sets and compared. But to say the Sony (with no local dimming and no Dolby Vision) 'held its own' would be a gross understatement. It remains an incredible set where all content looks fantastic. In the dark scenes, it won't get as dark as the Vizio, or an OLED. But there are no errors to speak of with the Sony. No blooming, no banding, no backlight zones dancing around the screen. I didn't expect the results I saw. BUT at the end of the day: I can live with a TV set with exceptional performance and picture that just doesn't get as dark as I would like. But that Vizio is just garbage in comparison.