What color did you apply it to? Everyone like something different. It's all in the eyes of the beholder. I like the souveran topper, and the P21S 100% also. I think stuff like the Dodo juice wouldn't be good over the wolfgang sealant. Well maybe diamond white, RB and hard candy. Aren't those the only clear ones?
I tried it on a few colors, actually. Regal Blue, Black, White, Silver, Champange, and a few others. I was on a quest to find the right combination, but for my taste I didn't find that Souveran helped. Everybody has their own eye for it though. I certianly wouldn't want to discourage anyone from trying it for themselves to see what their experience is.
Regarding other questions...
Fuzion isn't hard to use at all. It is just a little harder to remove than Sovueran. Both are incredibly easy to remove and much easier than buffing a polish off or even many other liquid waxes, but if you have to split hairs to find the differences, that is one of them between these two products. The Fuzion bites a little more and you can tell a difference.
Souveran is a great product, but for white or any other light colored car, it is a bit of overkill. You will get fantastic results from something like Signature II on light colors. If you have a dark color like red or black then Souveran is a must, but for white you are only going to be able to see like 70% of the benefit. The other 30% is just lost in the color and doesn't add anything. Those percentages are just numbers I pulled out of my ear, but you get the picture. Using Souveran on white is like using a cannon to kill a mosquito. It is designed to really set off dark colors, and while it looks great on white, you will get the same results on that color using Signature II and you can save the Souveran for the dark colors.
What a waste of a good wax.