Thanks for the reply, I was afraid of that.
There seems to be little in the way of documentation on the process or on ZF2 itself. I wonder if anyone can dig out some links for me or provide some advice on it from personal experience.
For example, If I am upgrading the ZF version and a non-trivial conversion is required, might it not just be better to do the upgrade to Laminas directly? I am sure that much of what it does is change the namespaces anyway.