Just a quick update.
I transited at FRA early Saturday. Arrived at the far end of Z, and departed from Z close in (Z25). The good news is that there's an intermediate security checkpoint about a third of the way towards the main building. I was third in line and security took 3 minutes. I then continued along the airside Z to my gate (via the Senator lounge:))
And there's also a Z to A floor change there, with a Schengen (inbound) border control point.
I don't know if there's a similar A to Z security/ border control point (exit). But it does show that the improvements at FRA haven't completely slowed down the process and there still are some convenient security points like before.
Though I'd still personally be allowing at least 2 hours between connections.