After downloading and installing James Miller's (I do believe it's James, not sure where Richard came from unless there are two philanthropic and experimental Millers out there) Advanced Flat picture style, I put it to the test. I will not be using it for three reasons.
1. When applying it to RAW photos in the Picture Style Editor it does something weird to the shadow detail due to the colour corrections in it which overlap (that's why there's a yellow exclamation mark icon next to them). There isn't a smooth transition of the lifted shadow tones into the rest of the tones.
2. When checking the histogram on the LCD it seemed to me that the dynamic range isn't increased, the tones close to the highlights and shadows are just made more grey, but the extreme ends of the histograms stay the same. The curve in the Profile Editor is a crude tool.
3. I can get cleaner results shooting with Faithful or Neutral and then raising the pedestal and lowering the gain in Color Finesse (beautiful plugin free with After Effects) - less noise and it just looks better.
Basically, Advanced Flat messes with colours and introduces more noise. You can get cleaner results with similar amounts of detail in post.
What do you guys think? Here's an over the top example of what I mean:

- Adv Flat.jpg (389.73 KiB) Viewed 97540 times