I'm pretty sure that the majority of the community would find this quite tantalizing.
Imagine, if you will, a button to the right of the four Blue Warp Placement icons on the lower panel that, when clicked, will yield a dialogue with a pulldown of all the FF Combos and a "Place" button and a "Cancel" button.
When you click the Cancel button, you will be able to click and drag the square icon around the screen, exactly as you would be able to do so with the warp arrival placement icons.
However, just as in grab mode, you'd be able to press the "s" key to toggle snapping to the grid, in terms of 1 pixel, 8 pixels, and 16 pixels.
Clicking or double-clicking would place the FF Combo right where the rectangle is. Then you can expand it towards its lower right in the usual FF Combo dialogue menu.
Thoughts?