I got and used the 603 this weekend. Really nice, and I think is the most useful. I'll be doing a better review shortly. I do want to add the 401 to my collection.
Unless you have really wide wheels, I don't think you need the 601 or 602. IMHO of course.
And my wash water was FILTHY afterwards, unlike I've ever seen cleaning wheels.
My one question yet, is to use it on low or high speed on my Makita drill. Fast really spits stuff around if you're not super careful. Slow seemed, well, a little slow.
