I completely agree with the prior posts, particularly ptaylor: "I love Zaino but this foolishness about hiding swirls is nonsense." Foolishness and nonsense are arguably redundant, but (I feel my toes burning already from approaching flames), I think Z2 and
Z5 are mostly redundant to each other.
I am a long time Zaino user who switched to Ultima about 6 months ago. Side-by-side on a trunk lid, Menzerna FP-II produced a glossier, more clear shine than Z-PC. Z-PC was quite good, and Menzerna-like in the way it worked with the UDM, but the FP-II was better. In addition, I believe that Ultima produces a brighter, more "wet" shine than Zaino. I've used it on our blue-green and our white cars, and Ultima really pops on both. I also find that Ultima seems to release bug guts and other tough dirt a bit better, but with our drought water restrictions, I've washed the Ultima so rarely that my experience is limited.
Also, Z2 or Z5 without ZFX doesn't last nearly as long. While I don't find adding ZFX to be a terrible thing, I've been resistant to buying a $20 tiny bottle of it, expecially when Ultima sealant is wipe-on, walk away and gives such great results.
If I was starting from scratch, I would go right to Ultima and skip Zaino. There are still some sample-size packs for under $50 from David, I think. If you have a PC, UDM or rotary, I would polish the paint to remove swirls with Menzerna SIP followed by FPII or 106, or use SIP followed by the Ultima PPP.