Is there really such a thing as a merely verbal dispute ?

It seems dubious, in general.  For people do not in general debate whether a certain expression S should or should not be assigned to a certain meaning M  or reference O , save for philological reasons such as in the Cratylus, etc.  Even then it is assumed that M and O have been correctly agreed upon and fixed by shared vocabulary.  There could be a dispute among lexicographers about what meaning a given linguistic community assigns to a given expression or whether a proposed definiens is apt. But this is not normative, or only secondarily in the sense that a speaker is then bound to conform to 'correct use'.  The idea of a merely verbal dispute has its origins, perhaps, in legal disputes, quid juris and quid facti. Thus is X A ?  can be seen as a debate either about facts or about the correctness of the correspondence of the facts with a legal deduction and definition.  But is does not seem very interesting if a common legal definition of A is not agreed upon. Rather the debate will involve details of deduction both legal and factual. Or else the definition can be meta-legal about proposals of new definitions, which is fine. But the intention being thus, there is nothing metalinguistic here.