What kinds of errors did you experience with Netatalk on the older Pi? I have a hard time believing that Pi hardware would be a limiting factor, unless there's something proprietary about the network interface / stack or something like that.If it helps, I tried using macippi on my pi 3b and ran into lots of issues with netatalk in general. It just does not like any pi older than a 3b plus. Guessing we are running into the same problems with it.
From JAG's description above, it sounds like afpd itself is running fine since it's possible to connect to the AFP share over TCP/IP. It's atalkd (AppleTalk daemon) that's erroring out.