If you make an adjustment (such as an increase in saturation) to the red color slice, does it apply evenly over the entire 45 degree range? If so, is there a sudden drop-off at the border between red and orange if no similar adjustment is made to the orange color? Does it work differently if you use the targeted adjustment tool and select a color on the photo that might not be in the middle of a 45 degree color range?
I'm pretty sure the HSL (which is actually following the HSB model, not HSL even if that's what it says in the UI) adjusts the colors in a way to have prominence at the peak of a color hue and tapers off towards the adjoining colors. In the case of the TAT, the sample of the color where the cursor is over will adjust 1 or two adjoining colors (I've never seen 3 colors move) in the same basic manner of prominence at the peak hue. If 2 colors are being adjusted I'm pretty sure everything between toe 2 color hues moves and the hue tapers off on the outside.
But this is really an Eric Chan question...