The local dimming on the TCL p series is decent, and improves the contrast ratio on our black checkerboard pattern significantly.

It isn't without some flaws though. On a side by side comparison, we found it to be better than the Vizio M Series 2017 but just a bit shy of the Sony X900E. Unfortunately, it darkens the moving white highlight too much compared to the Sony X900E. It is easier to see on the smaller highlights, but the behavior is present event with the bigger one. The darkening is more obvious when the moving highlight crosses the limits of each dimming zone. It seems the algorithm is a bit too aggressive here.

Update 07/10/2017: Testing with the latest firmware shows no visible changes to the local dimming performance. The algorithm remains very aggressive, often dimming small highlights and turning backlight zones on and off quickly instead of gradually as highlights move across the screen, which produces flashing as visible in the above video.

Update 07/17/2017: Enabling 'Game Mode' unfortunately disables local dimming, which means picture quality is a little worse in 'Game Mode'.

Update 08/01/2017: Local dimming now works with 'Game mode' enabled, as of software version 7.7.0 (build 4111).