Finally got around to using Snow Soap. I had washed my truck the day before so it was still clean. I wanted to a Mike Phillips aggressive wash to fully clean up from the winter. Truck got Iron X, which showed no reaction except a small spot on the hitch. After PW off, I put about 3oz of Snow Soap in my foam gun neat. I was surprised at how much foam it made, straight out of my gun. Even McKee xtreme foam didn't make as much. Since I already knew the paint was iron free, I wasn't expecting to find a reaction. I used the snow soap to serve as my lube for my nanoskin. After claying and washing, I PW again. This time I noticed that my LSP was gone, and the paint was not beading at all.
I wouldn't use snow soap on a regular basis, only for my spring clean up or before a full detail. I prefer to do Rinseless Washes, simply for its a lot less of a production with hoses and drying and such. I did think my truck was extremely clean when I was done. I still have to do a full clean up on the wife's car. I'll skip the Iron X on it and see if there will be any difference in how clean I can get.
Pros:
Cleans great
Very foamy
May react to iron
Good clay lube
Cons:
Too aggressive for regular use
Need to wear gloves
Can degrade LSP
Smells just as strong as regular Iron X