For shits and giggles, I changed my color depth to thousands and could barely notice a difference (on my MBP). The white background of web pages was the most noticeable thing oddly enough. If I looked vlosely I could see the dithering, but I didn't really notice it.
Also, I used SwitchResX and found my LCD panel to be the 9C60 model. I couldn't find a whole lot on it except that in some forums, people claimed "it is better". Better than what, I don't know.
: Use SwitchResX to generate a report which will tell you the model number of
: the screen used in your Mac. Google that model number and usually you can
: find a page that lists actual manufacturer specs. My MBP definitely has
: the 6-bit display, I see it whenever I scroll and there's a detailed color
: graphic on the screen.