Detailer's clay and decontamination are two different processes. The abrasives 'shear' the surface contaminates, the sheared particles are then encapsulated by the clay (i.e. the top of the metallic particle leaving the rest embedded in the paint, which acts as a conduit for moisture to the various paint layers, allowing it to continue generating corrosion damage
I could be wrong about the Sonax, I only tried it on a small area and didn't give it much dwell time but I saw no color change at all. I don't like using wheel cleaner on vehicle paint anyways, so I just rinsed it off and never tried it again. The powder-coating on wheels is much much stronger than vehicle paint so you can't just assume that if something is safe for your wheels, then it's safe for your paint. Legacy, as far as I've been able to tell, IronX doesn't do a darn thing to the wax, and its performance as a pre-wash is very similar to 1Z Anti-Insekt.
I beg to differ about it not removing wax. I just bought a white Pontiac Torrent and used IronX about 500ml for the entire vehicle. Vehicle was waxed prior and water sat on paint after Iron X so it clearly removed any hint of protection.
Wasn't going to but got some of the spray and also got some of the Full Effect wheel cleaner. I'll have to wait till it gets here to really start my spring clean up I guess but it'll be interesting to see how they work.
Sonax FE works on paint, but my feeling is that it's very mild. Here's how it worked for me. Before: Sonax FE applied (I use the trade version which over here is a clear liquid) After 2 minutes of working time: Little red dots start to appear: Rinsed with Kwazar Venus and dried. No adverse effects noticed under the Brinkmann: Use on your own caution!