I've had them on since early October, they are great have about 12k miles and still going strong. They are a little noisy but perform VERY well during the last midwest winter.
Just ordered a set of DWS for my CLS today.
Steelwool would be the way to do it, but getting a decent looking result will be VERY VERY difficult. If you were thinking about attempting I would get a scrap piece of metal, polish it up and then practice with the SW. You probably will not be happy.
I have no idea how the facia is attached on the lexus, but typically they are attached to the base radio unit with 4-6 plastic tabs and can be removed as a whole. I've repainted a few differant ones from various ford, gm, and others.