The Fanthom .5 writes more smoothly than the Frixion .4 which tends to be a
little scratchy, and it's handy not to have to remove the cap to access the
eraser. The colors of the Frixion are brighter, and the eraser works much better
than that of the Fanthoms. It would be great if Frixion would either move the
eraser to the end of the cap or make a block eraser.