This conversation has been merged. Please reference the main conversation: Lightroom: Gradient Eraser Request
Specifically, that once the grad filter is added, it could be further adjusted by adding to and especially removing from, with a brush tool.
For it to work, the brush tool would only affect the Alpha-channel that the grad filter created and not the underlying image.
Adobe could engineer it so that a right-click over the selected grad filter pin would create a (linked) brush option. When the option is selected, the view switches to a Graduated Filter Overlay (by default with the red mask active to remind you that you are adjusting the grad filter), and the tool has switched from the grad tool to an adjustment brush that only works on the grad filter.
You add to the grad filter by brushing, or by holding option/alt-brush to remove the grad filter. Using the flow/density modify tools would give great control in the same way that brushing a mask in a Photoshop adjustment layer does.
If you want to work on the grad filter directly (without the Overlay mask) then just keying O will switch to that view. Right clicking the grad filter pin gives you the option to switch back to standard grad filter behaviour.
If you now re-adjust the grad filter, the brush adjustments would need to stay in place relative to the pixels, not the grad filter.
If a further grad filter is placed over the brushed in area, a right click on the pin could load the previously placed alpha-channel brush adjustment so that a carefully brushed mask doesn't have to be created from scratch again.
Maybe this is complicating things too much, but hey! Sounds feasible and useful. Right?
Another useful addition to the adjustment brush is to have Shift-clicks to do contiguous straight lines, consistent with the way shift-brushes work in Photoshop. Very useful for deselecting grad-filtered or brushed areas around buildings and products.