For what it's worth, I'm pretty new to polishing (bought the Cyclo kit in July). I find that the Paint Correcting Polish does a great job on its own.
I don't really notice any difference when I follow up with the Paint Finishing Polish on my Silverstone S2000.
I think the Finishing Polish adds a bit more shine on my Carbon Black Regal GS, but it might just be because I really want it to.
In both cases, the paint was in pretty good shape to start. Light swirls/scratches only. I'm still working on both cars using both steps mainly because a part of me feels incomplete not following procedure doing only one out of two steps, not because I think I need to.
Been using only the foam pads on both cars so far; no microfiber yet.