I've been using the Mr. Clean kit for over 6 years now and can vouch for it, although IMO the soap isn't any better than the generic gallon jugs you find at your local auto store. The real key is the integrated filter, which is what ultimately prevents contaminates from creating spots. The one problem I've found is that if you use a higher-end car wash (Meguiar's NXT is what I use) the soap will be too thick for the gun to mix with the water. So I use the gun purely for the filter.
I've heard great things about the Ice product and have been meaning to try it for awhile now. In addition to what you listed, it supposedly is able to be applied in direct sunlight, which is important for those of us without garages in the hotter parts of the country.