I can attest to the effectiveness and usefulness of both the GWC and the Powerstick! Before i swapped out my semimet for ceramics this is what i had to deal with.
<a href="http://s627.photobucket.com/albums/tt351/GXPimpin/?action=view¤t=DSC01062.jpg" target="_blank"><img src="http://i627.photobucket.com/albums/tt351/GXPimpin/DSC01062.jpg" border="0" alt="Brake dust"></a>
Now mind you i wash atleast once a week (Mi weather permitting)
This is maybe a week and a half + since a wash ( I was waiting for the gwc and wanted a real quality test)
Before
<a href="http://s627.photobucket.com/albums/tt351/GXPimpin/?action=view¤t=FLBefore.jpg" target="_blank"><img src="http://i627.photobucket.com/albums/tt351/GXPimpin/FLBefore.jpg" border="0" alt="FL before"></a>
After
<a href="http://s627.photobucket.com/albums/tt351/GXPimpin/?action=view¤t=FLAfter.jpg" target="_blank"><img src="http://i627.photobucket.com/albums/tt351/GXPimpin/FLAfter.jpg" border="0" alt="FL After"></a>
Not only does it work it cuts down the time on the wheel clean. Before my caliper clearance was so small i had to wash the wheels then get in the car back up foot, then wash the area that was previously behind the caliper. Now.... Squirt,Squirt zip Zip, Rinse next wheel!