It might mean lots of work for someone, but what devs are we speaking of here, documentation devs or code devs? I suspect if the doc devs just shut up and got to work on the docs the code devs wouldn't mind at all.
More documentation is great, so yeah, if you want a formal spec, go for it.
Here's a tricky question you can start with:
Assume there is a fork consisting of max-block-size blocks. How deep a fork/re-organization MUST a conforming implementation handle? 6 blocks? 1000 blocks? as-many-blocks-as-there-are-in-the-chain blocks?
Does that imply that a confirming implementation MUST be running with a certain amount of memory, or MUST a conforming implementation be able to handle such a chain fork within a certain amount of time?
.. and once you answer all that: what if the network consists entirely of non-conforming implementations that take shortcuts and just assume that there will never be a re-org more than X blocks deep?