I went from UC to MEguar's UP and the results were really good. The UC finished off pretty smooth and very clear with no marring; at least on an older Subaru. Hitting it with UP increased the brilliance of the shine and took the surface from slick to slippery.
I've also been pretty impressed with UP's cutting ability by itself. I was able to do a pretty decent job of knocking out swirls and light scuffs with just the UP and a polishing pad.