A useful tool complementing GridMove is
MaxMax by KM Tools, which lets the user leave a margin at any edge of each monitor when maximizing windows. This allows GridMove-tiled windows beneath to be accessed by moving the mouse pointer to the edge of the screen and clicking.
This paradigm suits the idea of windows which don't completely reach the edge of the screen, as in
this glee60 grid quite well.
To work around the bug which sometimes limits the minimum margin on multiple monitors with different resolutions (and set values more quickly than clicking the up/down spinner arrows multiple times), use regedit to edit the keys directly at
HKEY_CURRENT_USER\Software\Marcin Nowok\MaxMaxCaveat emptor