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N 100/2.8 Makro-Sonnar: Similar to the C/Y Makro-Planar 100/2.8 in performance, which means excellent (although a bit behind the modern MP100/2). Edward Karaa has used both so he can tell you more.
You get native 1:1 on both the Contax lenses, though. I haven't used the N, but if it's like the C/Y, it has, in my opinion, nicer focus transitions for macro work than the Z* MP.