Yes, currently I pick the color from the spot where I will begin my next brush stroke (to get the color at this point of the gradient). To get the stroke darker/lighter automatically I changed the Value option in the presets to fade (so it starts a bit darker and gets lighter), also I activated Hue to get some variation on every stroke (fuzzy stroke). Changing the Color rate was my first idea to get the “autopick” like behavior, but this basically disables every setting under the Color section. Hue and Value are not applied to the “picked” (smudged) color only to the color which is currently set as foreground and is actually painted.
So, I already have a brush that does the changes in hue and value I need, but I have to pick the new base color every time. Sometimes I forget it in the heat of the moment so it would be cool if I could set up the brush in a way to pick up the base color. It would be convenient.