From what I have read you are correct - P21S and S100 are the same. On my silver Audi it darkens to me but you know this is all subjective.
I put two coats of FK1000P on the rest of the car over the last two days - nothing new and exciting. I'm not too happy with the look though, so I'll probably top it with something else in a few weeks. I also had a terrible time on the second coat - the first coat I did a few sections and buffed - worked great. Second coat I did the whole car which took about 45 minutes. It was dusting off and gathered in the cracks, dried on like cement. Different use experience than a lot of others for me, and I had it on thin enough that you had to look from an angle to see it. Also not a big fan of having to avoid the trim.
Does beading show it is still protecting? Debated. I think the combination of beading, sheeting, and feel is about all you can do though. More important is that this was a relative test, meaning I judged all as dead similarly. So while others might call a wax "dead" at different times, the order of which wax lasts longer under however you judge it should be the same.
I am surprised by the results based on my own cars in my own climate. The difference that color of a car and whether it is garaged makes more difference than I ever would have guessed before doing these tests, so much that I now question longetivity claims across the board. I mean, in the same climate, two coats of 476, FK1000P, and 845 lasted just under 3 months on a black car sitting outside, while Pete's 53, XXX, and AG HD are lasting 7+ months on this car stored 15' away in the garage.
