I've had a C7 65" for a couple of years. Due to my desire for 4k @ 120Hz, faster menu navigation, better all-around image processing, much improved near black, brighter game mode HDR tone mapping (even if a little less objectively accurate to EOTF) I've decided to upgrade to a C9 65".
My professional experience is that I work some successful Vegas shows as a projection tech and cinematographer. Here are my first impressions of how the C9 compares to C7. (I've also posted this in the C7 owner's thread.) (~3,000hrs with C7 and ~7hrs with C9 in the same dark, light controlled environment)
TL;DR: If what you care about is very critical image fidelity across all sorts of formats, menu and app navigation responsiveness, game mode HDR brightness, then I think this feels like a substantial upgrade from the C7. Cleaner, sharper, faster, smoother in all aspects. Anything older than a C7 (I had a C6 as well) and the quality gap is even wider. I'm surprised. Considering the lack of hardware supporting HDMI 2.1, I have no way of testing the performance there.
If anyone wants me to compare certain footage from the same source and share thoughts, I'm willing to do so provided I have the Blu-ray or link to content. (Also, I can upload to my GoogleDrive some high quality demo footage in SDR and HDR, if desired.)
Physically, C9 is heavier with a sleeker looking stand that I prefer. Grey backing & stand look a lot nicer.
Feels a bit larger due to the bezel's size decrease (I think it's from 1.1mm to .9mm).
Navigating the menu is much snappier, close to instantaneous.
TV internal speakers surprisingly decent.
Coming out of black is much nicer, near black no longer crushed, even when bt.1886 is engaged in SDR the black crush is improved. (This is a huge+ for me. I returned a B6 because of the crush and even the C7's amount of crush can get irritating.)
Image processing
C9 produces all around better images, especially concerning lower quality content. Noise reduction features work quite well without introducing too much negative consequences like smudginess, but it does soften some desirable high frequency details. The smooth gradation option low - high work quite well without absolutely ruining sharpness. It works especially well in older video games that have been given an HDR update (Halo 3's skyboxes can get pretty blocky.)
Screen uniformity, OLED 'streaks or striping' & color cast in white.
Much better, at least with this particular panel. Grey uniformity is perfect in all areas where I noticed it with my C6 and C7s. My C7 (which I also got lucky with) had some noticeable OLED vertical striping in certain just above black scenes. (Arrival 2016 would reveal the most banding). White seems slightly more punchy and cleaner, even at the same output of 120nits. My C7 can have a noticeable yellow blotchiness in 100% white and white in general never felt especially clean & punchy. The 100% white color cast in this C9 seems to veer toward magenta, but it's much less noticeable and at first glance feels more pristine -- I think magenta is more tolerable than an off-yellowish. Only when really dwelling on it is it noticeable. This C9 is as flawless as one could hope for, with only one light vertical banding streak on the mid-left side, very rarely noticeable, even when dwelling on it.
Motion performance in all areas seems improved and it hard to explain why.. it's just plain smoother in all content so far. The Black Frame Insertion in 60Hz+ SDR content is quite cool as it substantially improves motion resolution, but the brightness hit is substantial -- I hope they add the Low, Medium, High BFI options. Unstable 30Hz content, like Bloodborne on PS4 Pro, is VERY flicker prone and unusable. Yet very frame consistent 30fps like Driveclub works fine. (OLED light at 85 maintains 120nits with BFI in SDR). In HDR, I'm not really willing to live with the luminosity reduction, but with 4k/60p content, BFI provides a dramatic increase in motion resolution; it's night and day smoother.
Game mode HDR is, or rather feels, substantially brighter yet still looks "right," for the most part. It's hard now to tell any difference in fidelity from Game mode and Expert modes in SDR and HDR. I love it. HOWEVER, some HDR content is either mastered or converted oddly, resulting in lifted blacks (Uncharted 4 is one example). The C9's HDR bright highlight extender seems to exaggerate the lifted blacks, but it's grayed out in Game HDR modem which is funny because that's the inverse of previous models where Game mode was inaccurately locked in other ways. Checked with games running on a 2080Ti PC and PS4 Pro. Mortal Kombat 11, Forza 4 look stunning. Spiderman, Gran Turismo Sport, Horizon Zero Dawn, The Last of Us, all look dramatically better, imo, regardless of the less objectively accurate EOTF tracking.
Game mode SDR also looks indistinguishable from ISF modes, but why this couldn't be changed in previous models with software update boggles the mind. The Wide gamut game mode lock in previous models is really annoying.
Input latency with a PC in desktop (4k, 60p and 1080p, 120p) is fast and frankly hard to tell as up to nearly double the C7's (~21ms - C7 vs 14ms - C9). Even when side by side with a 144Hz, 1ms TN panel. The C9 feels equally as fast as that panel where the C7 maybe felt ever so slightly more sluggish. I thought this would be easier to feel but it's actually not quite as noticeable, but I'm glad it's faster nonetheless.
Basic SDR calibration with an i1 Display Pro:
ISF Dark Room and Game mode:
OLED Light 34 (120 nits)
Color Temp: Warm 2 with High Gain Red -6 (6500k)
